gd is a graphics library. It allows your code to quickly draw images
complete with lines, arcs, text, multiple colors, cut and paste from
other images, and flood fills, and write out the result as a .PNG
file. This is particularly useful in World Wide Web applications,
where .PNG is one of the formats accepted for inline images by most
browsers.

gd is not a paint program. If you are looking for a paint program, you
are looking in the wrong place. If you are not a programmer, you are
looking in the wrong place.

gd does not provide for every possible desirable graphics operation.
It is not necessary or desirable for gd to become a kitchen-sink
graphics package, but incorporates most of the commonly requested
features for an 8-bit 2D package.