Authentication is the act of confirming the truth of an attribute of a single piece of data claimed true by an entity.
In contrast with identification, which refers to the act of stating or otherwise indicating a claim purportedly attesting to a person or thing's identity, authentication is the process of actually confirming that identity.
Authentication is the process of ascertaining that somebody really is who he claims to be.Authorization refers to rules that determine who is allowed to do what. E.g. Bob may be authorized to create and delete databases, while Bobbette is only authorized to read.
In other words:
Authentication is your username + password. Authorization is what you're allowed to do.
It might involve confirming the identity of a person by validating their identity documents, verifying the authenticity of a website with a digital certificate, determining the age of an artifact by carbon dating, or ensuring that a product is what its packaging and labeling claim to be. In other words, authentication often involves verifying the validity of at least one form of identification - wikipedia 