There are basically four types of techniques which are given below :
* Cookies : Cookies are small information which is added to multiple client requests.
Example : One request comes to the server, the server adds some cookies with the response, now when again the same client sends the request to the server, the server recognizes the user.
* Hidden Form Field : Here we use a hidden text field for maintaining the state of the user.
* URL Rewriting : Here we give an extra link for the next servlet to be mapped.
* Http Session : Here a specific ID is generated for each user, so a server can recognize the user.
