Some file permission examples:

777 - all can read/write/execute (full access).
755 - owner can read/write/execute, group/others can read/execute.
644 - owner can read/write, group/others can read only.

Some directory permission examples:

777 - all can read/write/search.
755 - owner can read/write/search, others and group can only search.

Common permissions settings:

777 - directories with proper permissions on files in directory, use this one very carefully
755 - web store folder, CGI scripts
751 - log folder
701 - webalizer and modlogan folders
666 - data files
644 - configuration files (files not updated by scripts, html, gif,etc...)