noun

SSL

ESS-ess-EL

SSL (noun) means an older protocol for encrypting traffic between two computers over a network, now superseded by TLS. The name survives in everyday use, and "SSL certificate" is still the common term for the file that proves a site's identity and enables an encrypted connection. Example: “Their SSL certificate expired overnight and the browser started warning visitors.”

noun

technical An older protocol for encrypting traffic between two computers over a network, now superseded by TLS. The name survives in everyday use, and "SSL certificate" is still the common term for the file that proves a site's identity and enables an encrypted connection.

"Their SSL certificate expired overnight and the browser started warning visitors."

"The host installs SSL for you when you add a domain."

How to Use SSL

Learner’s notes

In plain EnglishSSL is the thing that lets a website encrypt what you send to it.

When to use it

Strictly speaking the protocol in use today is TLS; SSL persists as a loose everyday label, especially in the phrase "SSL certificate". Take "an" before it in speech.

Memory tip

A certificate does two jobs: it enables encryption and it vouches that the address you reached belongs to the certificate holder. It is not a badge of quality or honesty.

Trace the full origin ↓

Easily confused with

TLS HTTPS → certificate authority

Common pairings

SSL certificate install SSL SSL error free SSL SSL expired

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Fill the Gap

Can you complete this real example?

Their _____ certificate expired overnight and the browser started warning visitors.

Etymology

An initialism of secure sockets layer.

Origin: English

Synonyms

View more →

secure sockets layer TLS transport encryption

Frequently Asked Questions

What is the difference between SSL and TLS?

TLS is the successor to SSL. The older SSL versions are obsolete and no longer considered secure, and modern connections use TLS. The word SSL survives out of habit, mostly in the phrase "SSL certificate", which in practice means a TLS certificate.

What is the difference between SSL and HTTPS?

HTTPS is the web protocol; SSL, now really TLS, is the encryption layer it runs over. A site serves pages over HTTPS by using a certificate and the encryption that certificate enables.

What happens when an SSL certificate expires?

Browsers can no longer confirm the site's identity, so they show a full-page warning before letting anyone continue. The site itself is still there; the certificate simply needs renewing and reinstalling.