When you need to delete some files or other subject on a Mac computer, I believe that we all know drag them to the Trash, but do you often forget to empty the Trash to free up the disk space which are still took up by these junk files? In Sierra, you will be able to set an auto-empty for the Trash on your Mac.
In the previous version of Mac OS X, when the user delete a file or folder to the Trash, it won’t be removed immediately on the computer but stay in the Trash, and gradually, people may accumulate a lot of junk files in the Trash, which also take up the space of your drive, so it is indeed needed to do a clean-up for the Trash regularly, but many users usually forget to do so. In macOS Sierra, the computer OS become much smarter than before, and people will be able to set an auto-empty function the Trash, which enable the Trash to be cleaned without any manual action.
When you finish the above settings, the Trash will clean the items from your computer after 30 days, and you don’t need to delete them manually again, the space also can be freed up instantly and effectively.