adding metadata to GIF image

I recently discovered you can embed metadata keywords to your images by going to FILE>FILE INFORMATION. Upon doing so, I note you can do this with GIF images. Do the keywords ACTUALLY EMBED? In essence, reading into this, it is said you can only do it with JPEG and TIFF files. Anyone with experience here please explain.

Gif 89a provides support for textual comments but the comments add like a byte a character.

here is a link to everthing you want to know (or don't want to know about .gif files.

http://www.geocities.com/marcoschmidt.geo/gif-image-file-format.html