authentication

meaning in plain English

A way to prove that someone or something is real or genuine, like checking an ID to make sure it’s not fake.

Think of a lock checking a badge—authentication is the ID check that proves you’re the real deal.

for example

Before you can log in, the website asks for an authentication code sent to your phone.

Imagine you’re at a club and the bouncer checks your ID to see if it’s really yours. That check is authentication—it confirms you are who you say you are. Without it, anyone could pretend to be you.