In Vim visual mode, why does the command start with '<,'>?

Question

When I pop into Vim\'s visual mode to, for example, indent a block of text, the command prompt always starts with \'<,\'>. Can someone break down for me w

Answer 1

Once you select in Visual Mode e.g. five lines, then '<,'> means that you will execute the command in that region.

so :'<,'>s/replaceMe/WithThis/g will apply to only that selection