Software testing is a process, to evaluate the functionality of a software application with an intent to find whether the developed software met the specified requirements or not and to identify the defects to ensure that the product is defect-free in order to produce the quality product.
Manual testing is the process of testing software by hand to learn more about it, to find what is and isn’t working. This usually includes verifying all the features specified in requirements documents, but often also includes the testers trying the software with the perspective of their end user’s in mind. Manual test plans vary from fully scripted test cases, giving testers detailed steps and expected results, through to high-level guides that steer exploratory testing sessions. There are lots of sophisticated tools on the market to help with manual testing, but if you want a simple and flexible place to start, take a look at Testpad.