Just like dust and clutter can accumulate in hidden places in your home (you know... out of sight, out of mind) the same can be said for your computer. Hidden files and programs can accumulate over time that aren't necessary to hold onto, and can seriously slow things down. To free up space on—and hopefully speed up—your Mac or PC, try decluttering these often forgotten files and folders.
If you have a Mac...
Clear off your hidden archived iMessages
If you use the Messages app to send texts from your computer, there are probably backups of all your chat logs hidden in your files—and if you text often, the number of backups taking up space might surprise you. (I learned this the hard way a few months ago when I found every text I'd ever sent and received since 2013 backed up on my Macbook.) To delete them, follow these instructions from iGeeksBlog.
Double check iPhoto for Doubles
Do you use iPhoto to back up your pictures from your iPhone to your computer? If you haven't already double-checked your photos before (or every time you've uploaded them), it might be worth going back through your iPhoto library to make sure there aren't duplicates or extra photos you don't want to hold on to—like screenshots of things you don't need anymore.
Delete your previous iTunes libraries and duplicates
Sometimes your iTunes library can accumulate multiple versions of your songs, so to be sure you don't have any duplicates taking up space in your library, you'll have to go through your entire music library. But don't worry, you don't need to scan thousands of songs on your own—there's an easier way to do it using a setting in iTunes itself, just follow these instructions from Apple Support.
If you have a PC...
Do a disk cleanup to clear temporary files
As you open emails, browse the internet, download files and install programs, you wind up with a lot of temporary files taking up precious space on your PC, but it's pretty easy to track them down and get rid of them—just use your computer's disk cleanup option. If you've never done a disk cleanup before, here's how to do it in Windows 10.
Clear out thumbnails
While you're deleting your temporary files in disk cleanup, you can free up additional space by deleting thumbnails as well (simply check off "thumbnails" just like you would "temporary files" in the instructions above). Thumbnails are what show you previews of files before you open them, but that means that your computer has to generate them for every single file you have—which can slow everything down.
Delete Windows Updates files
When you update your PC, it saves a cache of all the files involved every time—and they can take up a ton of space on your computer. Your computer should delete them on its own, but it doesn't always happen, so you can clear them out manually by following these steps from CCM.
Options for both:
Clear your browser cache
How you clear out your browser cache depends on what browser you use (though the steps are all pretty similar on most browsers), but you should clean out your history and cookies from time to time to. Here's how to do so in Safari, Chrome, and Firefox.
Uninstall applications you don't use
Okay, so this isn't exactly a "hidden" thing, but if you haven't used an application or program in a long time, you may have forgotten it's on your computer taking up valuable space. On your Mac, go through your Applications folder and delete the ones you no longer need. On your PC, follow these instructions to uninstall them.