What’s Authentication?

In simple terms,

Authentication is the process of verifying the identity of a user or information.

This means it is used to prove that some fact or some document is genuine, true or valid. What happens is that a user confirms their identity by providing their credentials. This piece of information is shared between the user and the service or system where authentication is required.

For example, when you want to access your Gmail account from a new device, you will need to be authenticated before you can see all of your emails or create a new one. You must prove that you own the correct login credentials by entering a username/email and password combination. When these values match with the ones stored in Google’s database, you will be authenticated and granted access to the mail service.

Now that we have a clear idea of what authentication means, let’s try to understand how this process actually works under the hood in web applications.