The Heisei Era is the current period of Japanese History which started in 1989 after the death of Emperor Hirohito and the succession of his son Akihito to the throne. It is also used as a fan term for tokusatsu shows and movies that were released from the 1990s to present day.
In the cases of some franchises,the exact date of when it's Heisei era occurred may vary due to the hiatus of a franchise or a change of style or direction. (Ex. Godzilla films post-2000 are called the Millennium Era films and have little to no connections to the Heisei films).
Many advancements in special effects were made during the Heisei Era, including CGI and digital editing effects, new materials and manufacturing techniques for costumes and props for more detailed designs, and motion capture.
- http://en.wikipedia.org/wiki/Heisei_period The History of the Heisei Era on Wikipedia