# JSON Web Token Notes

JSON Web Token (JWT) is an open standard (RFC 7519) that defines a compact and
self-contained way for securely transmitting information between parties as a
JSON object.  This information can be verified and trusted because it is
digitally signed.  JWTs can be signed using a secret (with the HMAC algorithm)
or a public/private key pair using RSA.

Let's explain some concepts of this definition further.

* **Compact**: Because of their smaller size, JWTs can be sent through a URL,
  POST parameter, or inside an HTTP header.  Additionally, the smaller size
  means transmission is fast.

* **Self-contained**: The payload contains all the required information about
  the user, avoiding the need to query the database more than once.

# JSON Web Token Notes

JSON Web Token (JWT) is an open standard (RFC 7519) that defines a compact and
self-contained way for securely transmitting information between parties as a
JSON object.  This information can be verified and trusted because it is
digitally signed.  JWTs can be signed using a secret (with the HMAC algorithm)
or a public/private key pair using RSA.

Let's explain some concepts of this definition further.

* **Compact**: Because of their smaller size, JWTs can be sent through a URL,
  POST parameter, or inside an HTTP header.  Additionally, the smaller size
  means transmission is fast.

* **Self-contained**: The payload contains all the required information about
  the user, avoiding the need to query the database more than once.


## When should you use JSON Web Tokens?

Here are some scenarios where JSON Web Tokens are useful:

* **Authentication**: This is the most common scenario for using JWT.  Once the
  user is logged in, each subsequent request will include the JWT, allowing the
  user to access routes, services, and resources that are permitted with that
  token.  Single Sign On is a feature that widely uses JWT nowadays, because of
  its small overhead and its ability to be easily used across different domains.

* **Information Exchange**: JSON Web Tokens are a good way of securely
  transmitting information between parties.  Because JWTs can be signed—for
  example, using public/private key pairs—you can be sure the senders are who
  they say they are.  Additionally, as the signature is calculated using the
  header and the payload, you can also verify that the content hasn't been
  tampered with.

Add a When should you use JSON Web Tokens Section
Add a When should you use JSON Web Tokens Section