Modern operating systems have all the necessary tools on board. When someone logs in, they see only their own files and programs all of a user's local files are stored in a folder with the user's name.
There is no need for everyone in a household to have their own computer - family members, or even roommates, can share one.
"You can share computers quite wonderfully because you can create your own account for each user," says Peter Siering from c't magazine.
