In Manual Testing , Testers manually execute test cases without using any automation tools. Manual testing is the most primitive of all testing types and helps find bugs in the software system.

 Any new application must be manually tested before its testing can be automated. Manual testing requires more effort, but is necessary to check  automation feasibility.

Manual Testing does not require knowledge of any testing tool. One of the  Software Testing Fundamental is "100% Automation is not possible". This makes Manual Testing imperative.