What Is a .GID File?
You found a hidden .gid file next to an old Help file. It is a Windows Help index. Here is what it does and how to remove it.
What a .gid file is
A .gid file is a hidden index and settings file created by the old Windows Help viewer (WinHelp) for a .hlp file. It caches the help topic index and your window size/position so Help opens faster.
Why it exists
The first time you opened a legacy .hlp file, WinHelp generated a matching .gid beside it. It is auto-generated, not something you create.
Is it safe to delete?
Yes. WinHelp rebuilds it the next time you open the help file; you only lose the cached index and remembered window layout.
Note
Modern Windows no longer ships the WinHelp viewer, so most .gid files today are harmless leftovers from old software.
FAQ
Is it safe to delete a .gid file?
Yes. It is an auto-generated Help index; WinHelp rebuilds it, and you only lose a cached index and window layout.
What creates .gid files?
The old Windows Help viewer (WinHelp) creates one next to a .hlp help file.
Can I open a .gid file?
There is no reason to — it is an internal index, not readable content. Open the associated .hlp file instead.