What happens to computer files (like docs, pics, and so on***) when you delete them?

In windows and Mac they go in a folder usually called trash or recycle bin and my get compressed to save space. From there you can "perminatly" delete them or restore them. Once you "perminatly" delete them the computer tells the filesystem that the space where it was "is open" so it appears deleted but it isn't. The file technicaly is still there intill it is overwritten so if you had the proper program/computer skills you could still recover them but depending on the drives usages they might not come back as the compleat original file

All of your files are listed in the FAT (File Allocation Table)- When you delete them the pointer in the table changes from showing the files original path to showing it in the recycle bin.

When you empty the recycle bin, the first letter of the file name is replaced with a ? and the space marked as available. If you do a disk defrag, the original file will be overwritten

In a Windows based system they go into a temporary trash can folder until you permanently delete them.