For 24 hours (beginning at 12:00am EST on the 18th of January, year 2012), Wikipedia will go dark to the English-reading world.
The online encyclopedia made the decision to make such a bold statement in hopes of educating the masses on SOPA (Stop Online Piracy Act), and the immense negative effects and restrictions that it could bring to the internet if it were to be made law.
Wiki explains their motives on their homepage, with the following words:
Imagine a World
Without Free Knowledge
For over a decade, we have spent millions of hours building the largest encyclopedia in human history. Right now, the U.S. Congress is considering legislation that could fatally damage the free and open internet. For 24 hours, to raise awareness, we are blacking out Wikipedia.
More importantly, they provide all the information you need to learn everything about SOPA and the Protect IP Act (PIPA) on one of the few working Wiki pages for the day, and urge everyone to contact their local representatives to speak out against these acts ever becoming a reality.
You can head to their main page to enter your zip code to find out who to contact from your area and how.
Other sites taking part in the massive e-strike include Craigslist, BoingBoing, and Reddit.