Hi,

  Regression Testing Definition :-  After changes made in 
the application or After fixing some bugs - Application 
should not deliver any new bugs.

  How do you conduct manually - 
   by periodically - means definenite day , Tester take the 
latest code and do testing for given set of bugs.

Regards
Raghu

after retesting

regression testing is nothinng but reexecution of test 
cases on the modifies build to determine whether the 
defects clossed or not?

after getting bug fixed by the developer and received thru
for tester he want to conduct regerssion testing to check
whether the bug was fixed properly in an application.

here every body is giving answers for what is regression 
testing but the question was how to conduct regression 
testing manually can anyone give then answer...

verifing the build one or more times by manually.

According to ISTQB regression testing is testing of a 
previously tested program following modification to ensure 
that defects have not been introduced or uncovered in 
unchanged areas of the software, as a result of the changes 
made. It is performed when the software or its environment 
is changed.

Here only the defects which were raised by you will be 
picked up and tested.
 
Go to that perticular window where you found the defect and 
verify if it is working or not