A free, open-source file pager
GNU 'less' is a program similar to 'more', but which allows backward movement in the file as well as forward movement. Also, 'less' does not have to read the entire input file before starting, so with large input files it starts up faster than text editors like 'vi'.
Less uses 'termcap' (or 'terminfo' on some systems), so it can run on a variety of terminals. There is even limited support for hardcopy terminals.