umask, in short, says "when creating afile or directory, do NOT set the following bits that I have set in my umask". So a umask of 002 says "do not set the world WRITE bit during a create, even if they say to set it". A umask of 077 would say "never set any bits for world or group". You can go ahead and explicitly set those bits with chmod after the file is created if you want. It's just a rudimentary security tool thing ... to make sure people don't go around creating 777 files without knowing it. Most umasks only mask the world access bits, and sometimes group access bits.