Short answer
An SSL/TLS certificate is a file installed on a server that encrypts traffic between a browser and a website, turning http:// into https:// and removing the browser’s "Not secure" warning. Free certificates from Let’s Encrypt are the standard option and renew automatically. A certificate proves the connection is private, not that the business behind it is trustworthy.
Also called: SSL certificate, TLS certificate, HTTPS certificate
The failure modes are mundane. A certificate expires and every visitor meets a full-page security warning. A certificate covers example.com but not www.example.com, so half the traffic is blocked. A page loads over https but pulls an image or script over http, which browsers flag as mixed content and may refuse to load. All three are configuration problems rather than purchases.
Paid certificates still exist in organisation-validated and extended-validation forms, which involve a check on the company behind the domain. Browsers stopped displaying the green company name in the address bar years ago, so for a typical business site the visible result is identical to the free option. The case for paying is a specific compliance or warranty requirement, not visitor reassurance.
Common questions
Do we have to pay for an SSL certificate?
Usually not. Let’s Encrypt issues free certificates that most hosts install and renew automatically, and browsers treat them identically to paid ones. Paid certificates buy organisation validation and a warranty, which matter for particular compliance requirements and are invisible to visitors.
Related terms
Web Hosting
Web hosting is the paid service that keeps a website’s files on a server connected to the internet so visitors can load them.
Domain Name
A domain name is the address people type to reach a site, such as blackbyrds.digital, rented from a registrar in yearly terms rather than bought outright.
Uptime and Service Level Agreement (SLA)
Uptime is the percentage of time a service is available; a service level agreement is the contract stating the target and what happens when it is missed.
Reading definitions because you are scoping a project? Skip ahead and just ask.