For no particular reason, I decided to do a disk cleanup on my Win7 machine and one of the items they suggest to clean up are "thumbnails", for 35MB.

Can somebody tell what thumbnails are?

Mary,
You can read about thumbnails (condensed images) here http://en.wikipedia.org/wiki/Thumbnail

Some programs generate archives of these small images which can add to hard drive clutter. That is particularly true if the thumbnails are left behind after the full size image to which they pointed has been deleted.

How would I know if I should clean out these thumbnails? Are they important to viewing Internet sites?

A thumbnail is not a bookmark. I don't see how deleting a thumbnail could cause any problems but you might see a generic icon in place of the small picture if you actually use any of the thumbnails.

What program are you using to "clean up" your Win7 machine? Does the program give a list of the thumbnails it suggests you delete?

I was just using the Disk Cleaner installed on my computer. I never went far enough to see if it shows me any details; I'm just supposed to check, or uncheck, whether I want them to delete the thumbnail "files".

Mary,
I don't have a Win7 system so you might want opinions of those who do use Win7.

Here is how I see it. If your drive still has lots of space, then leave the thumbnails. If you think 35MB of space is critical, then delete the thumbnails but also consider adding another hard drive.

Personally, I don't see how removing the thumbnails would cause any problems.

I don't have any problem with leaving the thumbnails as they are; I have plenty of room. I just had never encountered them before when cleaning a disk.

I regularly clean the thumbnails - in addition to all the other junk - off my Windows 7 computer. I also have plenty of room - 1.5 TB - but, I like to keep any detritus cleaned up. Too bad my house doesn't look as good as my computers!

Draclvr,
Had never heard of "detritus" before. You never know what you're going to learn around here.

Well, detritus sounds a lot better than the word I would really liked to have used!

Ah, I gotcha!

Mary -

If you are talking about the thumnail.db files - you can safely delete them from any Windows Operating System. There are merely a cache index of the photos in that particular directory - They only serve, or claim to, speed up searching through your photos.

Good word Draclvr! No one can say "You waste your time " on this site - Never stop learning

Yeah, sureshot, I spent my entire career dealing with waste, so it's hard for me to get away from it!

Just saw your profile Draclvr