Intellipedia was formally launched in 2006, but grew slowly at first. “It was received skeptically by most,” said Carmen Medina, the former CIA director for the study of intelligence and one of the first officials to green-light the project. “Analysts were not really rewarded for contributing to Intellipedia.”

Since then, the wikis have grown steadily. According to a release celebrating the site’s second anniversary, the system housed nearly 50,000 articles by March 2008. In January 2014, the National Security Agency responded to a Freedom of Information Act request with the latest statistics: The three domains had just over 269,000 articles, more than 40 percent of which were found on the top secret wiki. (It’s not clear whether articles are duplicated across the wikis.)

Built on the same software platform as Wikipedia, Intellipedia's articles are often cribbed directly from the free encyclopedia, but with sensitive classified information added by analysts. “About everything that happens of significance, there’s an Intellipedia page on,” Sean Dennehy, one of the site’s founders, told The Washington Post in 2009. An article about the terrorist attack in Mumbai was filled with sensitive information before it was reported in the popular press, Dennehy said.

In 2009, Dennehy and Don Burke, both CIA analysts, won a Service to America Medal for their work on Intellipedia.

Their site is meant to help analysts collaborate across agencies: Improving cross-agency communication was one of the main recommendations set forth by the 9/11 Commission, which led to the establishment of the Office of the Director of National Intelligence in 2005. That’s the agency that now has custody of Intellipedia.

Unlike on Wikipedia, Intellipedia edits are tied to analysts’ identities. “We want people to establish a reputation,” said Thomas Fingar, the former Deputy Director of National Intelligence for Analysis at ODNI, at an event at the Council of Foreign Relations in 2008. “If you’re really good, we want people to know you’re good. If you’re making contributions, we want that known. If you’re an idiot, we want that known too.”

A number of Intellipedia pages have been declassified or made available to the public through FOIA requests. Some are silly, like the entry for Area 51, which, for some reason, briefly describes a cafeteria in Fort Bliss, Texas. Others, like the entry for the Nevada nuclear test site or for the Bay of Pigs invasion, are mostly filled with information from Wikipedia, but have short redacted passages that may contain classified details. A request for the page on Edward Snowden only turned up an empty placeholder. (A website called The Black Vault has compiled dozens of these FOIA requests and responses.)

Perhaps the best real-world example of how analysts use Intellipedia came in a recent story about Palantir, the secretive tech contractor led by Peter Thiel, published last month in The Intercept. Documents leaked by Snowden included pages from an internal wiki maintained by GCHQ, the NSA’s British counterpart, which included a link to a page about Palantir on Intellipedia. Other Intellipedia pages in Snowden’s leaks included links to other Palantir programs that the NSA uses, suggesting that the wiki is sometimes used for sharing technical information about intelligence software.

Intellipedia may have seen its traffic spike this week: If nothing else, the shoutout to the wiki in the Times might have sent curious analysts combing through the pages to see what intelligence was scattered there for safekeeping.