If you type ls -l, you can see file permission like below.

 
drwxr-xr-x 3 chang users 512  Jan 21 22:49 101 
-rw-r--r-- 1 chang users 2312 Jan 15 21:54 index.html 
drwxr-xr-x 2 chang users 512  Jan 15 16:54 javascript 
-rw-r--r-- 1 chang users 2859 Jan 12 16:54 work.html 

• First letter indicates if it is a Directory.
• Next each group of three characters indicate file permission
  • First three are permissions for owner, second three are permissions for the group, and last three are permissions for everybody. Every “-” means  no permission.
    • r: read
    • w: write
    • x: execute