SSL basics
This guide explains what SSL and TLS do, the difference between HTTP and HTTPS, and what the validation terms on a certificate mean.
SSL is the older name for the protocol that encrypts a connection between a browser and a server. Its successor is TLS. People still say SSL for both, and certificates are used for TLS connections.
- HTTP sends pages without encryption. Anyone on the network path can read them.
- HTTPS is HTTP over TLS. The connection is encrypted, and the browser checks that the certificate matches the site's name.
A certificate proves that a site's name belongs to the server. Encryption is the same whether the certificate is free or bought, when both are correctly installed and configured. Paid certificates offer different checks and support, not stronger encryption by default.
Validation describes how the certificate authority checked your control of the domain. Common terms are:
- Domain validation: the authority checks that you control the domain, for example by a DNS or email check.
- Organisation validation, and extended validation, check more details about the organisation. These are offered only where the product page says so.
Wildcard certificates cover one level of subdomains, such as *.example.com. Multi-domain certificates cover a list of names. Check the product page to see which types are offered.
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Last reviewed
2026-10-27