A plain-English guide for website owners: what SSL does, why it matters, and what to do when something goes wrong.
An SSL certificate is a digital file that does two things:
When a site has a valid SSL certificate, the browser shows a padlock and the address starts with https://. Without one (or with an expired one), browsers show a red warning that sends most visitors straight back to the search results.
Frequently asked questions
SSL (Secure Sockets Layer) is the original name for the technology. It was replaced by TLS (Transport Layer Security), which is what all modern websites use. People still say "SSL certificate" out of habit. The terms refer to the same thing in practice.
Yes. Google Chrome and other browsers mark any page with a login form, contact form, or even just a text input as "Not Secure" without HTTPS. This damages trust and increases bounce rates.
Google also confirmed HTTPS as a ranking signal, so even purely informational sites benefit from switching.
| Type | What it validates | Best for |
|---|---|---|
| DV (Domain Validation) | You control the domain | Blogs, small sites |
| OV (Organisation Validation) | Your company exists | Business sites |
| EV (Extended Validation) | Full legal verification | Banks, e-commerce |
| Wildcard | Domain and all subdomains | Sites with many subdomains |
A Certificate Authority is a trusted organisation that issues SSL certificates. Well-known CAs include Let's Encrypt (free, automatic), DigiCert, Sectigo, and GlobalSign. Your browser has a built-in list of trusted CAs. Certificates from unknown or untrusted issuers trigger a browser warning even if the certificate is technically valid.
A SAN is an extension that lets one SSL certificate cover multiple domain names. For example, a single certificate might cover example.com, www.example.com, and mail.example.com. Domain Checkup shows all SANs on your certificate so you can see exactly what is covered.
Browsers immediately show a full-screen "Your connection is not private" error. Most visitors will not click through. The effects include:
Since 2020, the maximum validity period for publicly trusted SSL certificates is 397 days (around 13 months). Let's Encrypt certificates are valid for 90 days and can be set to renew automatically. Many hosting providers auto-renew, but failed renewals are a common cause of outages, so it is worth monitoring.
For encryption strength, yes. A Let's Encrypt DV certificate provides the same level of encryption as a paid DV certificate. The difference with paid certificates is the validation level (OV or EV), warranty, and support. For most small-to-medium websites, a free Let's Encrypt certificate is perfectly sufficient.
Run a free analysis on Domain Checkup: it shows your certificate issuer, expiry date, and a countdown warning if renewal is due soon. For a detailed technical grade (including cipher suites and vulnerability checks), use the SSL Labs Server Test.
Check your domain's SSL certificate now. Free, no account needed.
SSL errors, mixed content warnings, or certificate renewal problems? Get personalised guidance from a domain and web infrastructure specialist.