here v go for automation testing ,to overcome the drawbacks 
of manual testing like time consumtion,man power etc

once the application is stable then only we can go for 
automation

Conducting repetative tasks on the same applcation is 
tedious process to over come this we go for automation 
testing and it is more reliable.
Here we can record the test scripts once and run these test 
scripts on each build of the application.Once regression 
testing is done and application is stable then only we go 
for automation testing.

Generally tasks are automated to reduce man power and to 
have good returns on investment. 

Automation is good candidate for Regression.

P.S. Feasibility study should help a lot for taking up any 
automation challenge.

Hi,

It is difficult to find all the errors in the manual
testing,some errors could be untouched in the manual
testing,and manual testing is a tedious testing.To overcome
all these drawbacks automated testing is done.

we can go for the automation 
1.when we want to consume the time
2.when application has so many repeatable functionalities
3.when there are so many functionalities with tedious 
processes
4.when we can expect the no of verssions of that software
5.when the application has enough time to testing with 
enough budjet

as we know that time is very precious during any 
development...
we need to utilise it in best possible manner.
we also need to produce a  bugfree solutions to the client.
so
overall
to increase the productivity with best quility is possible 
throght only automation......

we can go for automationonly for save money&time.In 
automation our work complet very fast .it's save time & 
money

In manual testing it is difficult to find errors, and it is 
time consuming, needs man Power.To Overcome all these 
factors automated testing is used.Automated testing is used 
only once the application is stable then only we can go for 
automated testing.

Automation testing is used when

1. Application needs a set of tests to be executed very 
regularly due to a software change or defect fix.

2. Application undergoes constant changes and needs 
regression tests to be reexecuted

3. Test expected results are clearly identified and 
documented and is not expected to change every now and then

4. Performance and load tests needs to be done with large 
volumes of data and user hits which are impossible to be 
addressed by the number of available testers

4. Data driven testing is needed regularly . for eg: if the 
same test requires to be executed 10 times with different 
input data sets, it is better to automate