User accounts and groups
The concept of a user account is nothing new. With it, you can have your own space, your own settings, your own file storage, whatnot, along with a password (hopefully) nobody else knows, to protect it. Linux is a multi-user operating system, which implements safe and advanced user account control, theoretically, there can be plenty of users or just one. On a home computer it is not likely to have hundreds of user accounts, but if it’s something like a family PC, you might find it useful to have more than one user account, so that everyone can use their own login details, and little Steve will never get to see daddy’s collections of… well… videos that explain how to fix cars, because little Steve is still too young to… well… fix cars.
The concept of groups might not seem that obvious at first glance. When talking about user groups, you might think of groups of users, that share some similar attributes. While probably makes sense in a certain angle and a certain light, under the right meteorological and astrological circumstances, it is probably best to picture groups as a collection of users that share a certain permission, or set of permissions.
This means, that whenever a user becomes a member of a group, the permissions granted to that group will then be granted to the user too. If you remove the user from the group, these permissions get automatically revoked from the user. This is a very effective way to handle multiple user accounts, or, on single-user systems, prevent the user to break stuff.
You should already know these permissions work (see the bit about file permissions in the previous chapter). How they can be granted revoked and changed, and how to assign users to groups, (or create new groups), will be covered in the next part, under Setting up users.