Both of my grandfathers (as well as two great uncles) served in World War II, and when I was young I would ask some general questions and get general answers. They're no longer around, unfortunately, but the more I learn about World War II the more questions I would have had for them. I remember a little about where they served and a few stories they had, but I'd really love to find deployment records for them.
The National Personnel Records Center in St. Louis has them. But they had a fire back in the '70s, that destroyed a lot of them. But they are diligently going through them restoring and/or archiving the millions of damaged records. If you put a request up with sufficient ID and date, they can make the effort to find something.
Hello there! As your question is related to looking for identification/information regarding military personnel, our Guide on Military Identification may be of use to you. It provides a number of different resources, including how to request service records from a number of national agencies around the world, as well as graphical aids to assist in deciphering rank, unit, and other forms of badges or insignia. While the users here may still be able to lend you more assistance, hopefully this will provide a good place to start!