HOWTO: abstracted DB table names

I've noticed that some modules seem to abstract the names of the DB tables by using brackets, for example in user.module:

SELECT * FROM {users} ....
or
SELECT r.rid, r.name FROM {role} ....

How do these get translated into the actual table names? When setting up new tables for my own modules, how can I do the same?

Instead of: SELECT * from mymoduletable ...
Use: SELECT * from {mymoduletable} where it may or may not have a table prefix.

The basic problem here is that I used a table prefix in production, but not offline, partially due to the sharing of an existing database in production while having full control of the offline copy. I don't want to change my code when uploading it to prod.

Thanks!