A package is a body of Macaulay2 source code devoted to a particular topic. Many packages are distributed with Macaulay2, and others are available from the author's homepage.
To load a package, say FirstPackage, enter:
loadPackage "FirstPackage"
or
needsPackage "FirstPackage"
For technical information about packages, see Package.
Macaulay2 searches for the file FirstPackage.m2 on your search path. The packages provided with Macaulay2 are on your search path, as is your current working directory.
Documentation for the packages provided with Macaulay2 is already installed. To install documentation for another package, use installPackage.
installPackage FirstPackage
You may see what packages have been loaded with the variable loadedPackages.