Here are some of the commonly used permissions:
755. This set of permissions is commonly used by web servers. The owner has all the permissions to read, write and execute. Everyone else can read and execute but cannot make changes to the file.
777. Everyone can read, write, and execute.
In a web server, it’s not advisable to use the “777” permission for your files and folders, as this allows anyone to add malicious code to your server. However, in some cases you’ll need to set the 777 permissions before you can upload any file to the server – for example: uploading images in WordPress.
644. Only the owner can read and write. Everyone else can only read. No one can execute this file.
655. Only the owner can read and write and cannot execute the file. Everyone else can read and execute and cannot modify the file.