Filters in AngularJS have two major uses.

Some filters work as the map function in Perl, Python, Ruby, JavaScript and in many other languages. They allow us to apply some transformation to one or more values at once. Among many other things this can be used to change how a single value is displayed.

Other filters are similar to the grep function in Perl, which is called select in Ruby, and filter in Python and JavaScript. These filters usually apply to a list of values and return a subset of the original values. They filter out certain values using some condition.