Memory Alpha is a collaborative project to create the most definitive, accurate, and accessible encyclopedia and reference for everything related to Star Trek. The English-language Memory Alpha started in November 2003, and currently consists of 26,872 articles.
Memory Alpha is a Wiki-model website with a format that would be familiar to anyone who has visited Wikipedia. Like the similar Wookiepedia (for Star Wars), Memory Alpha is not a general purpose encyclopedia, but rather a collaborative effort to collect all canon information about Star Trek in a single, centralized location. Non-canon information, such as that found in the licensed novels, can be found in its sister website Memory Beta, and there is frequently a link to Memory Beta at the bottom of Memory Alpha articles.
Memory Alpha was named after the United Federation of Planets central library, Memory Alpha, as seen in the original series episode The Lights of Zetar.
Although episode and movie reviews are not part of Memory Alpha's content, it does have a staggering amount of information on the episodes themselves, including production order, dates, cast and crew, major plot developments, spoilers, and behind-the-scenes looks at everything from the special effects models to excerpts from interviews with the production staff and screenwriters.
Other information available at Memory Alpha:
So if you're curious what year First Contact with the Vulcans occurred, or want to know the name of the treaty that prevented the Federation from developing cloaking technology, or just want to re-experience some of your favorite episodes by reading a synopsis, Memory Alpha is the place to get it.
My other favorite pop culture wikis: