The first user of a mark (provided there is no prior application pending) will generally acquire the exclusive right to use such mark within the areas of its "influence", i.e. within its marketing territory. Federal registration will give this first user the right to expand the use of the mark throughout the United States to the exclusion of at least those who have begun using the mark after the date of federal registration.
As stated, an application for Federal registration may be made by a party who has never used the mark in the U.S. This right to apply is limited to (i) certain foreign parties, or to (ii) parties with a "bona fide intent to use" the mark in the U.S.
The common law affords initial protection of the mark prior to Federal Registration. That is, until such time as Federal Registration is granted (and in the case that Federal Registration is never granted), the mark can be protected by state and federal laws governing unfair competition and trademark infringement. The protection of these laws does not require registration and is based primarily in the theories of (1) likelihood of confusion, (2) disparagement, (3)"palming off" and (4) other deceptive trade practices. Actions under these common law theories are brought separately in each or every state, and increasingly in federal court. State Registration of the mark can be accomplished but, in most cases, would appear to be of little value; although the value of a state registration should not be ignored.