[yvsanil]

Understanding access permissions
There are three types of permissions:

r read the file or directory
w write to the file or directory
x execute the file or search the directory

Each of these permissions can be set for any one of three types of user:

u the user who owns the file (usually you)
g members of the group to which the owner belongs
o all other users

The access permissions for all three types of user can be given as a string of nine characters:

user group others
r w x r w x r w x

[ScottHughes]

Thanks for giving this information. This is also useful for accessing files with PHP. I remember for a long time, I use to always forget the abbrevations for read and write file with PHP.