Wikipedia is the world’s fifth-largest website , the most commonly referenced encyclopedia and the first place people around the world go to when they are looking for facts and information . As a result, Wikipedia wields a tremendous amount of power in creating knowledge for the world. Since Wikipedia is a crowdsourced project, editable by anyone, it also represents a tremendous opportunity for people to help to shape this global knowledge.  It has redefined an encyclopedia as something which can be written by anyone and updated with to-the-minute news. 
The majority of Wikipedia editors are white, male and middle-class. Correspondingly, Wikipedia reflects the worldview of this social demographic, which is economically and socially privileged, as well as US/Eurocentric. According to the Wikimedia Wikipedia’s Editor’s Survey of 2011, “if there is a typical Wikipedia editor, he has a college degree, is 30-years-old, is computer savvy but not necessarily a programmer, doesn’t actually spend much time playing games, and lives in US or Europe.” 
The privileges–and blind spots–of this demographic’s worldview also mean that marginalized groups and their histories (people outside of the United States and Europe, people of color, poor people, women, LGBT people, and disabled people) are less represented (or less well represented) on Wikipedia. 
Tonight, I was invited by Wikimedia Sweden to a meeting about how to actively trying to change the fact that only 9% of the people who are taking part in editing and reviewing the content are women.  That fact means that discussions and other pages behind the scenes are also dominated and mainly created by men. This probably leads to a systematic bias towards a male-dominated worldview in what is written and for example in what is considered to be relevant in the notability guidelines.
On the English version of Wikipedia there is a project for countering systematic bias and in the last issue of the Wikipedia newspaper Signpost there are interviews with some of the participants in that project. The discussion we had today at Wikimedia related to if the pages behind the scenes of Wikipedia are strengthening this systematic bias, and what we could do to improve criteria, policies and other existing texts to counter that potential bias.
If you want to learn more about Wikipedia’s gender gap and the complicated reality of systemic gender bias and what you can do about it, you can read some of the articles linked below. If you can read Swedish, I can recommend a series of posts on Women and Wikipedia on the Wikimedia Sweden blog, including e.g. 10 reasons for women to edit Wikipedia and how to get more women to write on Wikipedia.
This blog post is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License, with citations and references from e.g.
 Wikipedia vs. the Small Screen, New York Times
 The Postcolonial Digital Humanities Rewriting Wikipedia Project
 Looking at the five pillars of Wikipedia as a feminist, part 2
 Kvinnorna, tekniken och Wikipedia