Following are the benefits of using Hidden fields :-
1.They are simple to implement.
2. As data is cached on client side they work with Web Farms.
3. All browsers support hidden field.
4. No server resources are required.
Following are limitations of Hidden field :-
1.They can be tampered creating a security hole.
2.Page performance decreases if you store large data , as the data is stored in pages itself.
3. Hidden fields do not support rich structures as HTML hidden fields are only single valued.Then you have to work around with delimiters etc to handle complex structures.
Below is how you will actually implement hidden field in a project
<input id="HiddenValue" type="hidden" value="Initial Value" runat="server"NAME="HiddenValue">