Imagine a customer entering your online store , starting to enter their payment card details, and suddenly their browser displays a red message: "Your connection is not private." Most users abandon their purchase at that point and don't return.
An SSL/TLS certificate is the foundation of every website these days – whether you run a store, a company blog, or a website showcasing your company's offerings. In this article, we explain what an SSL certificate is, how it works, which types are worth knowing about, and why not having one could cost you more than you think.
What is an SSL certificate?
An SSL (Secure Sockets Layer) certificate is a digital document that serves two functions simultaneously: it confirms the identity of the server to which the browser connects and activates encryption of all communication between that server and the user's device. Simply put, an SSL certificate ensures that data transferred between the website and the visitor is encrypted and unreadable to third parties.
It's worth noting that technically, SSL is the name of an outdated protocol. Its successor, TLS (Transport Layer Security), has actually been in use for years, and introduced significant security improvements. Nevertheless, the term "SSL certificate" has become so well-established that it still serves as a common industry shorthand for both technologies.
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What does this look like in practice?
When a user enters a website address in a browser, the browser sends a request to the server. The server responds with its certificate. The browser verifies its authenticity by checking whether the certificate comes from a trusted issuer (CA – Certificate Authority), whether it has not expired, and whether it matches the website address.
If verification is successful, an encrypted connection is established. This entire process—called the TLS handshake—takes a fraction of a second and is completely transparent to the user.
Encryption protects specific data: payment card numbers, passwords, data entered in contact forms, addresses, telephone numbers, and everything that the user provides to the website.
Without an SSL certificate, this data is transmitted in clear text, which can be intercepted, for example, on a public Wi-Fi network. A website address with a certificate begins with https:// , while one without a certificate begins with http://.
How to recognize an SSL certificate on a website?
The most obvious indicator is the URL – if it begins with https:// , the certificate is deployed. However, it's worth knowing the current appearance of security indicators in browsers, as they have changed in recent years.
HTTPS as a norm, not a distinction
Google Chrome removed the green padlock in 2023. It decided that HTTPS should be the norm, not the preference, so SSL-secured sites now display a gray, neutral padlock icon.
Meanwhile, websites without an SSL certificate are actively marked as "not secure" in Chrome, with this message appearing directly in the address bar. Firefox uses a similar approach. When a certificate has expired or is incorrectly configured, both browsers block access to the site and display a full-screen warning message to the user.
Types of SSL certificates
Not every SSL certificate is the same – they differ primarily in the level of verification of the domain owner's identity. Choosing the right type should be based on the nature of the website and the data it processes.
- DV (Domain Validation) This is a basic certificate that only confirms domain control. It's issued automatically in minutes and is the cheapest – often available for free through Let's Encrypt. It's sufficient for blogs, news sites, and portfolios that don't collect sensitive user data.
- OV (Organization Validation) requires additional verification of company details – name, address, phone number. The process takes several business days. It is suitable for company websites, services and institutions that want to give users the confidence that they are talking to a real organization.
- EV (Extended Validation) This is the highest level of verification – CA thoroughly checks the company's registration documents and the legality of its operations. Recommended for banks, online stores, and financial institutions, where user trust directly translates into conversions.
- Wildcard secures the root domain and all its subdomains (e.g., sklep.firma.pl, blog.firma.pl, panel.firma.pl) with a single certificate. This is a practical solution for organizations with a complex subdomain structure.
- SAN (multi-domain) certificate in turn, it allows you to cover many different domains with one certificate, making it useful for companies running several separate websites.
SSL certificate and user security and trust
The primary function of an SSL certificate is to protect against a man-in-the-middle attack – a scenario in which a third party intercepts communications between a user and a server.
SSL renders stolen data useless
In an unencrypted HTTP connection, this is technically straightforward, especially on public Wi-Fi networks in coffee shops, hotels, or airports. Captured login credentials, passwords, or payment information can be immediately exploited. An SSL certificate ensures that even if the data is intercepted, it remains encrypted and therefore useless to an attacker.
The business dimension is equally important. User behavior research consistently shows that the message that a site is unsecure effectively deters visitors, with a significant number leaving the site before they even have a chance to explore the offer.
For online stores, this means abandoned shopping carts and direct loss of revenue. For service websites , it means fewer completed contact forms.
SSL Certificate, SEO and GDPR
Google officially announced HTTPS as a ranking factor back in 2014. Since then, the importance of this signal has steadily increased – today, sites without an SSL certificate are treated as less trustworthy by the search engine algorithms.
Furthermore, full-screen warnings displayed by browsers to users who land on insecure sites lead to a sharp increase in bounce rates. Google interprets this as a sign of a poor user experience, further negatively impacting search rankings.
SSL and GDPR – legal obligation to protect data
From a legal perspective, the lack of an SSL certificate on a website processing personal data poses a significant risk. GDPR requires data controllers to implement appropriate technical measures to secure data transmission.
This applies to any page with a contact form, newsletter signup form, registration form, or shopping cart. Failure to encrypt the connection may be considered a violation of the regulations by the Office for Personal Data Protection, which may result in investigations or a financial penalty.
How to obtain and implement an SSL certificate?
The process of implementing an SSL certificate is much simpler today than it was a few years ago – most hosting providers offer installation in just a few steps or even with one click.
- The first step is to select the appropriate type of certificate – according to the criteria described earlier. For most corporate websites and blogs, a DV certificate from Let's Encrypt is free and fully sufficient. E-commerce sites and institutions should consider an OV or EV certificate from commercial providers such as DigiCert, Sectigo, or GlobalSign.
- Once you've obtained the certificate, you need to install it on your server—your hosting provider typically provides a dedicated panel for this purpose. The next step is to configure an HTTP → HTTPS redirect, setting up a rule that automatically redirects every visitor from the unsecure version of the address to the secure one.
- Finally, it is worth verifying the correctness of the installation using the SSL Server Test tool available on the SSL Labs website – this tool checks the certificate configuration and indicates any errors.
How long is an SSL certificate valid? Important changes in 2026
SSL certificates are not issued indefinitely – they have a specific validity period, after which they must be renewed.
Until recently, the maximum validity period was 398 days, but in April 2025, the CA/Browser Forum – an organization of browser manufacturers (Apple, Google, Mozilla, Microsoft) and the largest certification authorities – voted to gradually and radically shorten the maximum validity period of SSL/TLS certificates.
The timeline is as follows: from March 15, 2026, certificates can be valid for a maximum of 200 days, from March 15, 2027, for a maximum of 100 days, and from March 15, 2029, for a final validity of just 47 days. With a 47-day validity, each certificate will require renewal 7-8 times per year.
Protect your website from SSL expiration
For website owners, this means having to keep track of renewal dates, which becomes impractical and risky. Automating this process—made possible by the ACME protocol, which is being used by a growing number of commercial providers—is no longer a convenience, but a necessity. For end users, this change is purely beneficial: shorter validity periods mean fresher certificates and reduced risk.
The most common SSL certificate problems
Even after properly implementing an SSL certificate, issues can arise that cause your website to malfunction or display warnings. It's important to understand the most common issues and how to respond.
An expired certificate is the simplest and most common cause of problems – the browser completely blocks access to the website, displaying a full-screen error message. The solution is to renew the certificate in advance or enable automatic renewal.
Mixed content occurs when a page runs on HTTPS, but some of its resources—images, scripts, stylesheets—are loaded over HTTP. The solution is to update all internal references to HTTPS.
An incorrect redirect configuration causes users to reach an unsecure version of the website at http:// despite the implemented certificate – correctly setting the 301 redirect solves the problem.
Finally, a certificate that does not cover subdomains – a DV certificate issued for the root domain does not automatically protect subdomains, and in such cases a Wildcard certificate or separate certificates for each subdomain are required.
Frequently asked questions about SSL certificates
An SSL (Secure Socket Layer) certificate is a security standard that ensures the confidentiality of data transmissions over the internet. It works by advanced encryption of information exchanged between the user's browser and the server hosting the website. This protects sensitive data—such as passwords, PESEL numbers, or payment card details—from being intercepted by cybercriminals.
The presence of a certificate can be verified very quickly. In the browser's address bar, the URL for such a website begins with the prefix https:// (instead of the standard http://). Furthermore, a closed padlock icon appears next to the web address. Clicking on it allows you to view the certificate details and learn which organization it was issued to.
For online stores, SSL is an absolute must. Modern browsers (e.g., Google Chrome) are very strict about security. If you access a site without a certificate, the browser displays a discouraging red message saying "Not Secure" or "Connection Not Private." Such an alert drastically damages customer trust and almost immediately causes them to abandon their shopping cart.
Absolutely. Google has prioritized user security for years and has officially confirmed that HTTPS is a ranking factor. This means that sites protected by SSL certificates are favored by algorithms and have a greater chance of achieving high rankings in search results compared to their unsecured competitors.
Certificates differ in the rigor of verification of the entity for which they are issued:
- DV (Domain Validation): A basic certificate that only verifies your authority to manage a given domain. Issued instantly, it's ideal for blogs and simple informational sites.
- OV (Organization Validation): Requires verification of the physical and legal existence of a company (e.g., in the National Court Register). Recommended for corporate websites and smaller stores.
- EV (Extended Validation): The highest standard of authentication (formerly indicated by the green company name bar in browsers). It requires detailed document verification and is intended for banks, corporations, and large e-commerce platforms.
Free certificates like Let's Encrypt offer the same high level of cryptographic encryption as their paid counterparts and are perfectly sufficient for most blogs, business card websites, and small portals. Paid certificates (especially OV and EV) are worth choosing if you run a large online store or financial institution – they offer additional financial security in the event of a breach, visible company name verification, and dedicated technical support.
Summary
The above article covers the following topics:
- An SSL/TLS certificate is a mechanism for encrypting and verifying the identity of a server – today based on the TLS protocol, although colloquially still called SSL.
- Browsers actively warn users about sites without a certificate, instead of highlighting those that do.
- Types of certificates differ in their level of verification and should be selected for a specific website.
- Lack of SSL means real business losses – abandoned shopping carts, lower conversions, worse Google rankings and the risk of GDPR violation.
- From March 2026, SSL certificates can be valid for a maximum of 200 days, and ultimately in 2029 this period will be shortened to 47 days.
- The most common problems after SSL implementation are expired certificate, mixed content, incorrect redirection, and certificate not covering subdomains.
