A temporary implementation of part of a program for 
debugging purposes.

Its temparory program,stubs have called programs.

Its temparory program,stubs have called programs.

stub is a dummy program or component, the code is not ready
for testing,its used for testing...

Stub is a part of Intgeration Testing
Intergration Testing

1>Top down-Use stubs to test the module
Stub is a dummy module replaced in order to test the main 
module so that we are sure that the integration between 
both the modules works fine

2>Bottom Up-- Use driver to test the module
the test data is sent to main module thru the drivers(also 
called Test Harness)

Stub is nothing but programs when invoked by a other code 
segments it simulates as designed module functions which is 
yet to be constructed

stub is also include in Integration testing.
topdown & bottom up approch are included in Integration 
testing
topdown testing means It test to top module to sub module 
of the module .some times the developer has till not 
developed to the main module that time the temparary module 
is created that temparary module called "stub"
Bottom Up testing:It test to bottom to top means sub module 
to main module some times the submodule is till not 
developed that module is called driver

If any mistakes is thr please excuse

A dummy module is created in order to integrate modules of 
an application and can be tested for the convinience of the 
testers.
This is done usually in TOP down approach.