Some things are just better tested manually...
Manual testing is a process that does not use any automated tool or any script. To ensure the completeness of testing, we use the test plan, test cases or test scenarios on the software.
Manual testing also includes exploratory testing. This is running adhoc, pre-scripted tests/checks across a product or in a focused area of the product. This is often mentioned in a session-based Test Charter.
We have a default list of desktop browsers and devices where we perform our manual testing.