A cookie is used to identify a user. A cookie is a little record that the server installs on the client's Computer. Each time a similar PC asks for a page with a program, it will send the cookie as well. With PHP, you can both make and recover cookie value.
Some important points regarding Cookies:
Cookies maintain the session id generated at the back end after verifying the user's identity in encrypted form, and it must reside in the browser of the machine
You can store only string values not object because you can't access any object across the website or web apps
Scope: - Multiple pages.
By default, cookies are temporary and transitory cookie saves in the browser only.
By default, cookies are URL particular means Gmail isn't supported in Yahoo and the vice versa.
Per site 20 cookies can be created in one website or web app
The Initial size of the cookie is 50 bytes.
The Maximum size of the cookie is 4096 bytes.
