Automation testing is a process in which all the drawbacks of manual testing are addressed properly. and it provides:
 1. speed
 2. accuracy
 3. less time consuming
 4.simultaneous actions performed at a time

Automation tools will give the effective result than the manual testing, its a kind of 24*7 work environment with the tools

We can decrement the man power
More fast
More Reliable
More Effective
Regression can be done as many no of times
Thru automation tools we can reuse the generated script