Help provides access to the internal help system. This documentation is also available in HTML and PDF formats at https://docs.gimp.org.

The GIMP User Group offers an informative Web site at https://gug.sunsite.dk.

https://www.gimp.org is the official home page of The GIMP.

Grokking the GIMP by Carey Bunks is an excellent book based on an older GIMP version. Although some aspects of the program have changed, it can provide excellent guidance for image manipulation. An online version is available at https://gimp-savvy.com/BOOK/.