Permissions in unix are integral part of the operating system.
You can see the details of a file using ls -la command:
ls -la myfile
And you can see the details of all files in current directory by using:
Every file has a owner (also referred as user), a group and permissions. A user can be part of many groups. A group can have many users.
The permission attributes of a file signify who can do what.
15 Create File
17 Copy File