If you change computers but want to keep playing that one beloved game of "The Sims 3," you're in luck; save files are just computer files, which means they'll move to another computer without a problem. The destination computer doesn't need to be the same as the old one either; this means you can transfer a Windows save file to a Mac computer and vice versa.
On Windows 8, press "Ctrl+E" to open an Explorer window for "This PC." Open the "Documents" folder, followed by "The Sims 3." Here you will find a folder named "Saves" if you have an existing save. The folder won't exist until you've saved "The Sims 3" for the first time. You can copy the individual save files, but it's safest just to copy the entire "Saves" folder when you make the transfer. If you use a Mac, the folder path is the same; open Finder to reveal the Documents folder.
Put a USB stick into an available USB port, opening the drive in Windows Explorer. You can click and drag the "Saves" folder directly onto the USB drive without worrying about losing the original file; since it's an external drive, it will make a copy instead of moving it. Insert the USB drive in the destination computer and open the drive, dragging the file to the same "Saves" folder. If the folder doesn't exist on the destination computer, you can create it yourself.