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SSL/TLS certificate

Also known as: SSL certificate, TLS certificate, HTTPS certificate, digital certificate

The digital ID card that proves your website is really yours and switches on the padlock — without it, browsers warn visitors away.

What it is

An SSL/TLS certificate is a small digital file that does two jobs. It proves your website is genuinely yours (a trusted authority has vouched for it), and it switches on the encryption that scrambles everything passing between your site and your visitor — the padlock you see in the address bar. “SSL” is the old name; the technology in use today is really TLS, but most people still say “SSL certificate.”

Certificates have an expiry date and must be renewed, usually every few months. Many providers now renew them automatically.

Why it matters to your business

If your certificate is missing, expired, or doesn’t match your web address, the visitor’s browser throws a full-page red warning — “Your connection is not private” — before they ever see your site. Most people turn back at that point. To a customer it doesn’t read as a technical glitch; it reads as “this business is not safe.”

A valid certificate is also what lets visitors trust that the page asking for their card or login details is the real one, not an impostor.

How to tell / what to do

Our free checker tells you in plain language whether your certificate is valid, who it’s for, and how soon it expires — so an expiry never catches you out. If there’s a problem, the certificate fix guide walks through getting a valid one in place. It’s free, and on most modern hosting it can be set to renew itself automatically.

Want to fix this on your own domain? See the free guide →