All about Steins;Gate

Anime

Steins;Gate originally was a visual novel, the anime adaption was created later by Funimation and studio White Fox in collaboration with Nitroplus. It consists of 24 episodes and also has a special 25th episode which is set after the original series.

As an introduction to Steins;Gate Zero, an alternate ending to episode 23 has been released. Episode 23 β was translated by WhyNotSubs and can also be viewed on YouTube.

Info:

Announced: June, 2010
Released: April 6, 2011 - September 14, 2011
Episodes: 24 + OVA
Adaption of: Steins;Gate Visual Novel

Movie

The movie, Steins;Gate: Fuka Ryouiki no Deja vu, is set after the original series, about 1 year after the the special 25th episode.

Info:

Announced: September 13, 2011
Released: April 20, 2013
Runtime: 90 minutes
Adaption of: Fuka Ryouiki no Déjà vu Manga (Untranslated)

The Sagacious Wisdom of Cognitive Computing

This short series was made in collaboration with IBM and it consists of four episodes. It's supposed to be an advertisement, but it's still very enjoyable.

Info:

Announced: September 13, 2011
Released: October 14, 2014 - November 11, 2014
Episodes: 4

Steins;Gate Zero

Steins;Gate Zero is the sequel to Steins;Gate, which was announced on the 28th of March in 2015. The visual novel has been released, but its anime adaption has not started airing yet.
It will take place in the beta attractor field and it's based on the Epigraph Trilogy which can be found in the Manga & Light Novels section, and Drama CD Beta which can be found in the Drama CDs & OSTs section.
The visual novel has been released in Japanese, the English translation has been announced in May 2016 for PlayStation 4 and PlayStation Vita.

Info:

Announced: March 28, 2015
Released: -