SSL certificate: what it is and why every website needs one

SSL certificate: what it is and why every website needs one
20.11.2025

With most websites switching to HTTPS, the question ‘what is SSL’ has become fundamental for any web resource owner. Without SSL, data between the browser and the server is transmitted in plain text and can be intercepted: passwords, email, payment information, personal data.

With an SSL certificate installed, the connection is encrypted, the browser displays the address with https:// and a padlock icon, and the user receives a clear signal: this site can be trusted. For commercial projects, application forms, personal accounts, and online payments, SSL is not an option but a prerequisite for normal operation.

What is an SSL certificate?

What is an SSL certificate?

An SSL certificate is a digital file installed on a web server that confirms the authenticity of a website and allows a browser to establish a secure connection with it. In simple terms, it is a website’s ‘passport’ + a tool for encrypting data between the user and the server.

Technically, SSL (Secure Sockets Layer) is a security protocol on which the more modern TLS (Transport Layer Security) is based. In everyday life, the familiar name ‘SSL certificate’ is still used, although in fact we are talking about TLS. The certificate contains information about the domain, the company (if it is a commercial certificate), as well as an open cryptographic key, which is used to establish a secure HTTPS connection.

When an SSL certificate is correctly installed and valid, the browser can verify that you are actually connecting to the correct website, and all transmitted information (logins, passwords, payment details, forms with personal fields) is encrypted and cannot be read by third parties during transmission over the network.

Types of SSL certificates

Types of SSL certificates

SSL certificates differ not only in price, but also in how the website owner is verified and what security features they offer. The right choice determines the level of trust in the resource, the formality of company verification, and the convenience of further work with domains. Let’s take a closer look at the different types of certificates.

There are three main types of SSL certificates based on the level of verification of the website owner:

  • DV (Domain Validation). Only your control over the domain is verified: via an email to your work email address, adding a DNS record or a file to your hosting. This is the simplest and fastest option. Suitable for blogs, landing pages, small websites where there are no complex financial transactions, but basic encryption and no ‘connection not secure’ warnings are required.
  • OV (Organisation Validation). In addition to the domain, the organisation is also verified: legal name, registration details, contact information. The certification centre confirms that there is a real business behind the website. This type of certificate is appropriate for online stores, services with personal accounts, and corporate websites where users leave more than just their email address.
  • EV (Extended Validation). Extended verification with the most stringent requirements. Domain rights, company registration, contacts, and documents are verified. This option is for banks, payment services, and large online projects where trust and security are critical issues.

In addition to the level of verification, SSL certificates differ in how many domains and subdomains they can protect at the same time. This affects the structure of the project and how you will manage certificates in the future.

In terms of protection, SSL certificates are classified as follows:

  • For a single domain. Protects one address: for example, example.com or shop.example.com. If you only need to encrypt data on the main website or a single subdomain, this option is sufficient.
  • Multi-domain / SAN certificates. Allow you to protect several different domains with one certificate: example.com, example.ua, project-example.com, etc. This is convenient when a company has several separate websites (for different products or markets) but does not want to purchase and renew a separate SSL for each one.
  • Wildcard certificates. These protect the main domain and all its first-level subdomains: *.example.com, example.com, blog.example.com, client.example.com, pay.example.com, etc. This option is suitable for services with a branched structure, personal accounts, regional or functional subdomains.

For a small website, a DV certificate for a single domain is usually sufficient. If you have several projects, regional versions, or separate subdomains for services and accounts, it makes sense to immediately set up a SAN or Wildcard scenario with the appropriate level of verification.

Verification of SSL certificate validity

Verification of SSL certificate validity

Before entering your password, email address or card details on a website, it makes sense to take a few steps to check whether the resource uses HTTPS and whether its SSL certificate is valid. You can do this without any additional tools, directly in your browser.

The main way to check in your browser is as follows:

  1. Open the desired website and pay attention to the address: it should start with https://, and there should be a padlock icon next to it.
  2. Click on the padlock icon in the address bar. In the window that appears, the browser will show the connection status (for example, ‘Connection is secure’).
  3. Go to the detailed information about the certificate (a button like ‘Certificate is valid’). Here you can see who the certificate is issued to (domain, sometimes the name of the organisation), who issued it (certification centre) and until what date it is valid.
  4. Make sure that the certificate has not expired and that the certification authority is on the list of trusted authorities (Let’s Encrypt, Sectigo, DigiCert, GeoTrust, etc.).

If the certificate is expired, issued by an untrusted organisation, or configured incorrectly, the browser will usually display a full-screen warning labelled ‘Insecure connection’ and advise against proceeding. In such situations, it is not advisable to enter any personal or payment details.

Additionally, website owners can check the certificate using ‘Developer Tools’ (Security tab) or special online SSL analysis services. They show the full certificate chain, encryption strength, and possible configuration errors.

But for the average user, a simple rule is enough: if there is a padlock, there is HTTPS, the certificate is valid and issued by a well-known centre — the connection is set up correctly.

Basic types and methods of data encryption

Basic types and methods of data encryption

SSL/TLS makes the connection between the browser and the server ‘closed to outsiders’ through encryption. The idea is simple: even if someone intercepts the traffic, they will only see a set of random characters, not logins, passwords, or card numbers. To do this, a combination of two approaches to encryption is used.

In cryptography, two basic methods are used to protect data:

  • Symmetric encryption. The same key is used for both encrypting and decrypting data. This method is very fast and well suited for encrypting large amounts of traffic. The downside is that this key must be securely transmitted to both parties.
  • Asymmetric encryption. A pair of keys is used: public (open) and private (closed). The public key is available to anyone and is used only for encryption, while the private key is stored on the server and used for decryption. This scheme is slower, but it allows you to securely ‘agree’ on a shared secret without transmitting it in plain text.

An SSL certificate combines these two methods into a hybrid scheme: asymmetry is used only at the start to exchange secrets, and then all connections are encrypted using a fast symmetric algorithm.

How it works in practice (simplified SSL/TLS scheme):

  1. The user opens the website via HTTPS. The browser requests a secure connection from the server.
  2. The server responds by sending an SSL certificate with a public key and information about the domain/organisation.
  3. The browser checks the certificate: who issued it, for which domain, whether it has expired, and whether it trusts this certification authority. If something is wrong, the user sees a warning about an unsafe connection.
  4. If the certificate is valid, the browser generates a unique symmetric key for this session, encrypts it with the public key from the certificate, and sends it to the server.
  5. The server decrypts this session key with its private key. Then all traffic between the browser and the server is encrypted with this symmetric key.

As a result, a third party can technically ‘see’ the fact of the connection, but not the content of the transmitted data. The user only sees a padlock and https:// in the address bar, while all the complex cryptography happens automatically in a fraction of a second every time they visit a website with an SSL certificate configured.

HTTPS protocol: definition and role in website security

HTTPS protocol: definition and role in website security

HTTPS (HyperText Transfer Protocol Secure) is a secure version of the HTTP protocol that runs over SSL/TLS and encrypts traffic between the browser and the server. When a website switches to HTTPS, all user data – logins, passwords, email addresses, payment information, and any data from forms – is transmitted via an encrypted channel rather than in plain text.

This means that traffic remains confidential: even if it is intercepted, it is impossible to decrypt the content without the keys. At the same time, the integrity of the information is preserved, since it cannot be changed unnoticed during transmission. The authenticity of the website is additionally confirmed: the browser verifies the certificate with the domain and a trusted certification centre, so the user connects to the real resource, not a fake one.

For the visitor, this looks like a padlock and the https:// prefix in the address bar, but these markers signal that the connection is secure. For the website owner, HTTPS is a basic requirement for forms, personal accounts, authorisations, and online payments. Without it, modern browsers mark the resource as ‘unsafe,’ which directly affects conversion, trust, and search engine rankings.

Why does your website need an SSL certificate?

Why does your website need an SSL certificate?

An SSL certificate is not just a box to tick on a technical checklist. Without it, the website essentially operates in open mode: any data entered by the user can be intercepted, and modern browsers directly warn about unsafe connections.

This affects all critical points at once: personal information security, brand trust, legal compliance with data protection requirements, and search competitiveness.

When an SSL certificate is installed and correctly configured on a website, it is not only the protocol in the browser bar that changes. A secure channel for information transfer appears, alarming warnings disappear, users are more willing to leave their contact and payment details, and the resource itself looks modern and reliable.

How SSL protects users’ personal data

How SSL protects users' personal data

When a website operates over HTTP, any data entered by the user is transmitted over the network in plain text. Passwords, email addresses, full names, delivery addresses, bank card numbers, and personal account login details become vulnerable. Over an unsecured connection, they can be intercepted, replaced, or used for further attacks. This is the area of risk that an SSL certificate covers.

After SSL is installed, a secure channel is formed between the browser and the server. The data that the user enters into the form is encrypted in the browser, sent to the network in this form, and only then decrypted on the server. A person or programme that finds itself ‘in the middle’ (for example, on a public Wi-Fi network) sees only a set of encrypted characters, not the original text.

When working with personal information, SSL performs three important functions at once:

  • ensures confidentiality by converting human-readable data into an encrypted stream that cannot be read without keys;
  • maintains integrity by preventing the content of messages from being altered unnoticed on their way from the browser to the server;
  • confirms authenticity by allowing the browser to verify that the user has connected to your domain and not to a fake copy of the site.

As a result, your login, password, card number, or any other personal data on a website with properly configured SSL does not ‘travel the network’ in plain text. For the user, this looks like the usual padlock in the browser, but from a security point of view, the difference between HTTP and HTTPS is fundamental: in the first case, data is easy to intercept, in the second, it is practically impossible to use even if the traffic is intercepted.

The impact of SSL on website trust and reputation

The impact of SSL on website trust and reputation

For users, the presence or absence of SSL is easily recognisable by two things: the padlock icon and the absence of browser warnings. If, immediately after going to a website, a person sees a red screen with text about an ‘insecure connection,’ their trust is immediately lost. Even if the resource is useful, most people simply close the tab without looking into the details.

With HTTPS, the situation is the opposite: the user sees the familiar lock, calmly enters their email, password, card number or delivery details. The visual signal from the browser works as a simple labelling system: ‘it’s safe here’ or ‘it’s risky here’. For online stores, online booking services, educational platforms, or personal accounts, this directly affects the number of applications, payments, and returns to the site.

In addition to the behaviour of individual visitors, SSL shapes the overall perception of the brand. A website with security warnings looks outdated and neglected, even if the design and content are up to par. A secure resource with a correctly configured certificate is perceived as the minimum standard for responsible business. As a result, SSL directly affects not only technical security, but also how customers evaluate your website and company as a whole.

SSL and compliance with legal and regulatory requirements

SSL and compliance with legal and regulatory requirements

Data protection on a website is not just a matter of technical security or user trust. For most projects that work with personal or payment information, it is also a requirement of legislation and industry standards. Using an SSL certificate and operating the website via HTTPS helps to meet the basic level of these requirements.

In EU countries, the General Data Protection Regulation (GDPR) requires companies to ensure an adequate level of security when processing and transferring personal data. One obvious way to meet this requirement is to encrypt information ‘in transit,’ i.e., during its transfer between the browser and the server. A secure HTTPS connection with a correctly configured SSL certificate provides this encryption.

If online payments are made on the website, additional standards come into play, such as PCI DSS (Payment Card Industry Data Security Standard). Payment systems and banks expect card data to be transmitted securely. In such cases, having an SSL certificate and enforcing the use of HTTPS is not a ‘recommendation’ but essentially a mandatory element of the infrastructure.

The wording varies from country to country, but the essence remains the same: if you collect, store or process personal data, you are expected to take technical security measures. SSL does not cover all legal risks, but it is a basic requirement without which it is no longer correct to talk about compliance. For a website owner, this means that encrypting traffic via SSL/HTTPS is not only about a secure lock in the browser, but also about minimising claims from regulators, banks and payment providers.

How SSL certificates affect search engine rankings

How SSL certificates affect search engine rankings

An SSL certificate is directly related not only to security, but also to the visibility of a website in search engines. Modern algorithms assess whether a website operates over HTTPS and, all other things being equal, give preference to resources with a secure connection. For Google, this is an ‘easy’ ranking factor: it will not bring a website to the top on its own, but the absence of HTTPS can be a disadvantage in a competitive niche where many players have already switched to a secure protocol.

User behaviour is also important. If the browser warns of an ‘insecure connection,’ some visitors will not even enter the site, while others will quickly close it. This increases the bounce rate, reduces session duration and the number of pages viewed — and it is precisely these behavioural signals that search engines take into account when evaluating the quality of a resource. When a website runs on HTTPS and does not trigger alarming warnings, users are more likely to stay, interact with the content, and complete their intended actions.

An SSL certificate affects SEO in two ways: as a technical signal for the search algorithm and as a tool that improves behavioural metrics by eliminating warnings and increasing trust in the site. In practice, a website without HTTPS in a competitive environment finds itself at a disadvantage, even if the content and external links are of the same quality.

The role of SSL in protecting against cyber attacks and malicious actors

The role of SSL in protecting against cyber attacks and malicious actors

Any website without SSL operates as an open channel: all data is transmitted in plain text, creating ideal conditions for man-in-the-middle attacks. All an attacker needs to do is be on the same network as the user (e.g., public Wi-Fi) to intercept logins, passwords, authorisation tokens, or payment details. An SSL certificate eliminates this possibility: traffic between the browser and the server is encrypted, and even if intercepted, the attacker will only receive a set of encrypted characters without the ability to decrypt them.

The second important line of defence is protection against content substitution. On unprotected HTTP traffic, a third party can not only read data, but also change it ‘on the fly’: substitute fake login forms, change payment details, insert malicious scripts or advertisements. When a website operates over HTTPS, data integrity is controlled by cryptographic mechanisms: any invisible modification breaks the encryption and makes the connection invalid.

SSL also makes life difficult for phishing sites. The browser checks the certificate against the domain and the trusted certification authority, and if attackers try to impersonate another resource, the mismatch will be detected. The user receives a warning or sees that there is no lock and the connection is not marked as secure. This does not eliminate the need to be careful with links, but it significantly reduces the chances of a real website being replaced by a copy without being noticed.

At the same time, SSL is not an ‘antivirus for everything’; it does not protect against vulnerabilities in the website code, weak passwords, or malicious plugins. Its role is different: to create a secure communication channel, ensure encryption, integrity and authenticity of data exchange. Combined with updated software, strong passwords, two-factor authentication and basic cyber hygiene, this significantly reduces the possibilities for most typical attacks on users and their data.

What do you need to do to obtain an SSL certificate?

What do you need to do to obtain an SSL certificate?

Obtaining an SSL certificate seems like a technical task, but in practice it is a sequence of several straightforward steps. The logic is always the same: select the required type of certificate, pass verification, and correctly install it on the server, followed by transferring the site to HTTPS.

The main steps are as follows:

  1. Determine the needs of the website. You need to choose the level of verification (DV, OV, EV) and the type of protection (single domain, multi-domain, wildcard) depending on whether it is a small website, an online store, a bank, or a large corporate infrastructure.
  2. Select a provider. SSL can be purchased from a certification centre, domain registrar, or directly from a hosting provider. For basic protection, free Let’s Encrypt certificates are often sufficient, while commercial solutions from well-known certification centres are used for OV/EV.
  3. Generate a certificate request (CSR). This is done on the server or in the hosting control panel. During generation, a pair of keys is created: the private key remains on the server, and the CSR is sent to the certificate provider.
  4. Pass verification. For DV, it is usually sufficient to confirm control over the domain (letter to the official email, DNS record, file on the website). For OV and EV, the organisation’s details and the right to act on its behalf are additionally verified.
  5. Install the certificate on the server. After the certificate is issued, it must be added in the control panel (cPanel, Plesk, other admin panel) or manually on the server, linking it to the required domain.
  6. Enable HTTPS for the website. You need to update the main website address in the CMS, convert internal links to https://, set up a permanent redirect (301) from HTTP to HTTPS, and make sure there is no ‘mixed content’ where some resources are still loaded via an unsecured protocol.

After these steps, it is worth checking the website in your browser and using online SSL analysis tools, as well as setting up automatic renewal or reminders about the expiry of the certificate. This allows you to maintain protection without any security gaps when the certificate suddenly becomes invalid.

Conclusion

An SSL certificate transforms a regular HTTP site into a secure resource with an encrypted HTTPS connection. With it, open data transmission disappears, and logins, passwords, payment information, and other personal data pass through the network in encrypted format. This simultaneously reduces the risks of data interception and substitution, minimises the possibility of man-in-the-middle attacks, and complicates the work of phishing resources.

At the same time, SSL affects the visible side of the site’s operation: it removes browser warnings about unsafe connections, forms a basic level of trust, helps to meet personal data protection requirements, and maintains competitiveness in search results. In today’s environment, not having a certificate means working with constant reputational, technical, and legal risks, while switching to HTTPS is becoming the standard for any project that collects or processes user data.

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