There are 2 types of techniques 
1.	The first is a selective technique which identifies the
modified structural attributes of a program (required
elements) and selects a retest able test case set to
exercise them. This technique is based on the potential-uses
criteria family and is implemented by a regression-testing
tool working in conjunction with a testing tool.
2.	 The second technique comprises procedures for testing
and regression testing activities. These procedures make use
of the first technique to select a retest able set
containing test cases capable of checking up on the
potentially modified functionalities. The retest able set
provides a good coverage of the structural required
elements. Finally, empirical results show the effectiveness
of the techniques

Regression testing is the process of validating modified 
parts of the software, hoping that the modification does 
not introduce errors that were not exists before the 
modification. An important different between regression 
testing and development testing is that during the process 
of the regression test, a set of established tests can be 
reused. Regression test cases is a set of test case aiming 
at testing the core function or procedure of the software; 
core function means where procedure call with known input 
is made and the output of the function will be compare with 
output the developer expect. The set of test cases will 
then be reused for later development as incremental 
process, as development gets progress the size of the 
regression test will also be increase. In other word, the 
regression test result in greater test coverage, having 
greater coverage will eliminate the amount of errors/bugs 
in the end product, which is the ultimate goal of having 
test cases. Another advantage of the regression test is 
that all the tests are automated; all the test cases that 
gather before will be run all together without manually 
inputting date and comparing the output. These can 
significantly increase the efficiency of the testing 
process in developing a software product.