The integration Testing is doing for integrated modules. So 
first of all we required an integrated application to do 
the integration testing.

Here we have to check wether the integrated modules are 
working properly or not. This can be do through the 
integration test cases.

For example Creating a user account and login to the system 
are two modules.

Here u can see the Create User is a module and Login user 
is another module. So First we create a user then with the 
new username and password we logon to the system. If it is 
working as per the expectation then the test is pass.

Is it Clear?

we can follow the two approaches in Integration Testing-
Bottom up Integration and Top Down Integration....

Sanjay

We can do integration testing by integrate two 
modules.after unit testing we do integration testing.We 
folow two approaches for integratiion testing 
1. Incremental: follow a particular sequence
2. Nonincremental: doesn't follow a particular sequence
Top-Down approach and Bottom-Up approach comes under 
incremental and BigBang comes under NonIncremental

WHAT IS MEANT BY INCREMENTAL AND NON-INCREMENTAL TECHNIQUE 
IN INTEGRATION TESTING?