Chmod numbers

From dghartung.com/docs

4 = read
2 = write
1 = execute

      |-----Owner Permissions
      ||----Group Permissions 
      |||---World Permissions
chmod 755

7= read, write, execute
6= read, write
5= read, execute
4= read only
3= write, execute
2= write only
1= execute only

Change permissions through an entire Folder

chmod -R 755 folder/

Scope!