Filemaker databases can be shared, Filemaker allows 9 other Filemaker users to concurrently access the database.
Filemaker Server and Filemaker Server Advanced increase the number of concurrent Filemaker users.
Filemaker databases can be accessed by web browsers using Instant Web Publishing or PHP.
Filemaker Pro Advanced can create single user, not networked, one user at a time runtimes.
Filemaker databases can not be accessed by other applications. (As Access can not be opened by other apps)