I would dearly like to know what "Other" means in the About this Mac box when viewing Storage

I recently found to my horror that the hard drive on my iMac 20" (Early 2008) was showing only 24 available Gb. Granted, I have a good quantity of Raw files stored on the screen in 6 folders ( will be 7 at the end of September).


What I would seriously like to know is what 'Other' means when I opt to view storage. This is what I see:Screen Shot 2017-09-05 at 06.45.18.png

I know I have a good number of emails stored in Safari mail as well as some in Yahoo mail. Why don't Apple give us some idea as to what 'Other' might consist of in terms of file types or where the majority of the storage might exist?


For what it's worth, a large part of my files relating to photos are on a WD MyCloud external drive with 4 Tb capacity.


Any help would ease my fears of the HD going t**s up.

iMac, OS X El Capitan (10.11), Pixma 925, WD My Cloud, iPad Mini 3

howapple - hello


Thanks for the Kappy link. That just about encompasses what I asked in the first place.