As wikis become a bigger part of our lives, we owe ever greater thanks to those who keep them as clean and accurate as possible. In a letter on the site, Wikipedia’s founder, Jimmy Wales, writes, “Commerce is fine. Advertising is not evil. But it doesn’t belong here. Not in Wikipedia.” Keeping advertising out, however, requires hard work and dedication. And surviving without advertising requires the support of readers. Not everyone who reads Wikipedia can afford to donate to its mission, but it’s worth remembering the amount of work that goes into keeping the site free of promotional content, and also keeping it just plain free.