What do read, write, and execute permissions mean for a directory?

Read permits listing directory entry names. Execute, also called search permission, permits traversing the directory and accessing an entry when its name is known, subject to the entry’s own permissions. Write permits modifying directory entries, usually together with execute permission. Deleting a file therefore depends primarily on its parent directory permissions, with sticky-bit and other controls potentially restricting it. File permissions alone do not describe every access decision: ACLs, mount options, and mandatory access controls can also apply. Explain the actual operation before changing modes.