Caching is a technique of persisting the data in memory for 
immediate access to requesting program calls.

ASP.NET provides the flexibility in terms of caching at 
different levels
1)Page Level Output Caching
2. Fragment Caching
3. Application Level Caching


Caching is a technique that definitely improves the 
performance of web applications if one is careful to have a 
balance in terms of which data needs to be cached and 
parameter values for expiration policy.

Caching is a concept of storing frequently used data into
temporary memory. 

caching at different levels

1. Output Caching (Page Level)
2. Fragment Caching
3. Application Level Caching

Hi all this is Nizath Ali,

       Caching is a technique, used to improve the 
performance of a web application. It temporarily storing 
the frequently used data for the web application on the 
local hard disk for later retrieval.
       (If multiple users access the web application on a 
web server, The problem of slow access will occur. To 
overcome this problem ASP.NET provides "Caching".)
        There are 3 different levels of caching, 
1. Output Caching (In this type of caching the data for the 
entire page is cached. It is Page Level Caching.)
2. Fragment Caching (In this type of caching the data for 
only the specific sections of the page is cached.)
3. Data Caching (In this type of caching all the 
frequently  accessed data is cached in server side memory 
variable. It is Application Level Caching.)