Retesting: Applying multiple set of data to check for the
functionality like -ve and +ve data

Regression testing: say for example my project will release
as versions. version 1.0 is released and the next release
came say version 2.0. In 2.0 new functionality they are
adding new things to the old version. so at that time we r
checking new functionality and version 1.0 test cases also.
this is called as regression..

in oneword due to new functionality we r testing if anything
happens for the old funtionality or not.

Test case templete:

Test Case ID	Requirement ID	Test Case Scenario /
Description	Prerequisite / Setup	"
Step No."	Test Steps	Expected Result	Actual Result	TC Status	"
Test Cycle #"	"
Issue Tracking (Issue ID)"	"
Date tested on"	Remarks	"Automation
(Y/N ?)"	Priority

Retesting means: checking the existing funtionality or 
coding of the module

Regression means: checking the existing funtionality with 
the help of new inputs or datas weather its make any 
problem in futures like that.....

regression testing can be applied at any level of 
testing.These are tests that are run every time a change is 
made to the software so that we can find that the change 
has not broken or altered any other part of the sw program.

regression testing is an important strategy to reduce the 
side effects.

retesting is one in which we test the same piece of sw in 
which the changes are made with different values.

SDLC means Software Development Life Cycle
STLC means Software Test Life Cycle. STLC ia a part of SDLC.

test plan details the operational aspects to execute the 
strategy.

A test case is an unique combination of inputs with an 
expected output.

test case template consists of  TCID, TYPE, DESCRIPTION, 
EXPECTED, ACTUAL.