Cookies

A cookie is a small amount of data that is stored either in a text file on the client file system or in-memory in the client browser session. It contains site-specific information that the server sends to the client along with page output. Cookies can be temporary (with specific expiration times and dates) or persistent.

You can use cookies to store information about a particular client, session, or application. The cookies are saved on the client device, and when the browser requests a page, the client sends the information in the cookie along with the request information. The server can read the cookie and extract its value. A typical use is to store a token (perhaps encrypted) indicating that the user has already been authenticated in your application.

Note:

The browser can only send the data back to the server that originally created the cookie. However, malicious users have ways to access cookies and read their contents. It is recommended that you do not store sensitive information, such as a user name or password, in a cookie. Instead, store a token in the cookie that identifies the user, and then use the token to look up the sensitive information on the server.