A software package is a special method for the distribution and installation of software on computer systems.
The most common type of software package seen by the average computer user is that found sold in stores. An example might be a popular word processor. A user would purchase the software, then follow the given instructions to install the software on their home machine.
A very common type of software package is that found on many Unix-like operating systems. These are often a single file containing many more files to be installed, along with rules describing what other software needs to be installed for the package to function properly.
Common types of single-file packages include Redhat's RPM, Debian's DEB, and Slackware's TGZ.
See also:
Package management system