Error Guessing is a technique to find any bug through tester's experience. The main purpose of Error Guessing is to focus the testing activity on areas that have not been handled by other formal techniques. If the tester has prior experience on what he is testing, he can assume possible errors that might occur and he can include those test cases, making his testing more effective.
Why we use Error Guessing?
Error Guessing is a technique by which a tester can save his time on spent testing. Error guessing technique is considered as an effective test case design technique.
Draw Back of Error Guessing.
The main limitations of Error Guessing is that it totally depend on tester's experience,who is deploying it.