The Encyclopedia features very detailed information about characters, planets, technologies, ships, and behind-the-scenes information, as well as brief synopses of series program installments and motion pictures. It is replete with illustrations, many of which are in color in later editions, from examples of different writing systems to the evolution of uniforms and shuttlecraft.
In the time since its last publication, the Encyclopedia has become extremely out of date, with much of the conjectural, non-canonical information contained within it having been contradicted by the last two Star Trek films (Star Trek Nemesis and Star Trek) as well as the last two seasons of Star Trek: Voyager and the most recent series, Star Trek: Enterprise. There are currently no plans to release an updated version of the Encyclopedia, as its usefulness has been greatly superseded in recent years by online, digital resources such as Memory Alpha.
The print version was later complemented by a similar electronic version, the Star Trek Omnipedia. The CD-ROM medium allowed the Simon & Schuster publishers to include video clips.