How do SSL certificates protect websites, and why are they needed?

SSL certificates, combined with properly configured HTTPS, protect data transmitted between a browser and a website’s server, reducing the risk of eavesdropping, tampering, or impersonation of the server. Payment details are not the only information that needs protection; login passwords and form submissions do too. Free certificates also serve a security purpose. However, a protected connection does not mean every aspect of a website is secure, and certificates cannot replace website updates and other safeguards.

Protecting data in transit—not just adding an S to the URL

Standard HTTP transmits information in plain text, leaving it vulnerable to eavesdropping, tampering, and hijacking. HTTPS uses SSL/TLS to provide three types of protection:

• Encryption: Prevents passwords, credit card numbers, and other information from being exposed in plain text during transmission.
• Authentication: Helps verify the identity of the server you are connecting to.
• Integrity protection: Helps prevent data from being altered in transit.

For example, when a visitor submits a login form, the protection applies to the data’s journey from the browser to the server. Although the term “SSL certificate” remains common, the old SSL protocols have been replaced by TLS. The familiar name should not be taken to mean that the old protocols should be enabled.

Websites without shopping features need protection too

The need for HTTPS should not depend solely on whether a website accepts payments. Member logins, contact forms, and similar features also involve data exchange. Tenten’s 2022 article explicitly recommends certificates even for websites without e-commerce functionality. The point is to protect visitors’ connections, rather than waiting until credit card data is involved to consider security.

However, certificates have limits to what they validate. For example, domain validation certificates primarily verify control of a domain; they do not provide comprehensive information about the business entity. HTTPS alone therefore does not establish that a website’s operator or the transactions it offers are trustworthy.

Free certificates help; price is not the only criterion

Free does not mean there is no encryption protection. Semrush’s 2023 article lists ways to obtain certificates from hosting companies or certificate providers, including both free and paid options. For website administrators, more concrete checks include:

• Whether the certificate is valid and covers the web addresses actually in use.
• Whether pages are actually served over HTTPS, rather than merely having a certificate installed.
• Whether each subdomain in use is protected by a matching certificate.

For example, if a website has a separate shop.example.com address, a certificate for the main site does not necessarily cover the shop subdomain. If there is a name mismatch, check the certificate and replace it with one that covers the required names.

Beyond certificates, websites still need ongoing maintenance

The core role of SSL/TLS is to protect connections; it does not justify claiming that a website cannot be compromised. Websites still need regular updates to their content management systems, plugins, and themes, along with appropriate security monitoring and firewalls. Certificate validity also needs ongoing checks: installation is a starting point, not the completion of all security work.