IPS is a file format for binary patches, commonly used to patch game ROMs. The format is described at zophar.net.
Often when you run across a patch file, people want you to install some freeware patcher, which is hard to trust. Better to write my own patch program than risk getting some kind of crypto virus :)
The main program here applies a patch file to a target, but I also made a library with IPS-writing capability. This way, I can easily write programs that create patches as well.