Testing is an essential part of software development since it lets you measure software quality. Without testing, there is no way to verify that the software works correctly and bugs may be littered throughout the application and left unfound.
Testing is often done manually, by testers performing operations, step-by-step, and indicating whether a particular step was accomplished successfully or whether it failed. However, manual testing is a full-time effort, costly and often prone to human error.
To improve the efficiency of your testing, the testing process can be automated. Test automation allows companies to perform consistent and repeatable tests, save time and money, and improve the testing coverage. Unlike manual tests, automated tests perform precisely the same operations each time they are run, thereby eliminating human error and even cutting costs. Automated tests also run a lot faster, faster than any person could perform a manual test, so this allows companies to run more tests against their application. See Why Automated Tests?