GAP and its sources, including packages (sets of user contributed programs), data library (including a list of small groups) and the manual, are distributed freely, subject to "copyleft" conditions. GAP runs on any Unix system, under Windows, and on Macintosh systems. The standard distribution requires about 300 MB (about 400 MB if all the packages are loaded). To run GAP, 128 MB of RAM is sufficient.
The user contributed packages are an important feature of the system, adding a great deal of functionality. GAP offers package authors the opportunity to submit these packages for a process of peer review, hopefully improving the quality of the final packages, and providing recognition akin to an academic publication for their authors. As of August 2006[update], there are 58 packages distributed with GAP, of which approximately 35 have been through this process.
An interface is available for using the SINGULAR computer algebra system from within GAP. GAP is also included in the mathematical software system Sage.
gap>G:=SmallGroup(8,1);# Set G to be a group of order 8.
<pc group of size 8 with 3 generators>
gap>i:=IsomorphismPermGroup(G);# Find an isomorphism from G to a group of permutations
gap>Image(i,G);# The image of G under I - these are the generators of im G.
Group([ (1,5,3,7,2,6,4,8), (1,3,2,4)(5,7,6,8), (1,2)(3,4)(5,6)(7,8) ])
gap>Elements(Image(i,G));# All the elements of im G.
[ (), (1,2)(3,4)(5,6)(7,8), (1,3,2,4)(5,7,6,8), (1,4,2,3)(5,8,6,7),
(1,5,3,7,2,6,4,8), (1,6,3,8,2,5,4,7), (1,7,4,5,2,8,3,6), (1,8,4,6,2,7,3,5) ]