October 26, 2001 -- President George W. Bush signs the USA Patriot Act into law.
July 10, 2008 -- President George W. Bush signs the FISA Amendments Act into law.
December 1, 2012 -- Edward Snowden reaches out to Glenn Greenwald using the pseudonym "Cincinnatus," urging Greenwald to set up a secure communication channel. Greenwald ignores him and the two don't connect until Snowden appeals to Laura Poitras. Snowden and Greenwald begin communicating about NSA programs by April 2013.
May 20, 2013 -- Edward Snowden flies to Hong Kong after taking a leave of absence from his job at Booz Allen Hamilton, a contractor to the NSA. Greenwald and Poitras followed soon after, as did Guardian investigative reporter Ewen MacAskill.
June 6, 2013 -- The Guardian and The Washington Post publish reports revealing the Prism program, which lets the National Security Agency grab people's emails, video chats, photos and documents from some of the world's biggest tech companies. The companies denied giving the NSA unfettered access to such data.
June 21, 2013 -- Snowden turns 30 years old. The US Department of Justice unseals charges against him for violating the Espionage Act of 1917 and theft of government property
June 23, 2013 -- Snowden flees to Moscow, where he remains today.
Here, Snowden is shown on a livestream during the Right Livelihood Award ceremony at the Swedish Parliament on December 1, 2014. He was awarded the Right Livelihood Honorary Award for revealing the extent of state surveillance.
Here, Lavabit founder Ladar Levison is interviewed by CNET News' Declan McCullough at CBS Interactive headquarters in San Francisco, Calif., on October 27, 2013.
May 19, 2014 -- Greenwald, Poitras and Ryan Devereaux, a reporter for The Intercept, report the NSA is recording every phone call in the Bahamas and another nation, but decline to name that country because they say it would incite violence. WikiLeaks founder Julian Assange says the unnamed country is Afghanistan, causing a public argument between The Intercept and WikiLeaks on Twitter.
June 30, 2014 -- Admiral Michael S. Rogers tells The New York Times he has seen terrorist groups change communications tactics over the last year, but adds, "You have not heard me as the director say, 'Oh, my God, the sky is falling.'" Rogers was three months into his tenure as director of the NSA, replacing Keith Alexander.
June 2, 2015 -- USA Freedom Act enacted. The law reauthorized many provisions of the Patriot Act, but introduced some limitations on bulk collections of phone records.
July 31, 2013 -- The Guardian publishes a report on the XKeyscore program, which allows NSA analysts to access a huge variety of Internet traffic by querying databases with email addresses, phone numbers and other search terms.