Terminal pager

A terminal pager, or paging program, is a computer program used to view (but not modify) the contents of a text file moving down the file one line or one screen at a time. Some, but not all, pagers allow movement up a file. A popular cross-platform terminal pager is more, which can move forwards and backwards in text files but cannot move backwards in pipes. less is a more advanced pager that allows movement forward and backward, and contains extra functions such as search.
Some programs incorporate their own paging function, for example bash's tab completion function.