A teen-ager believed to be a leading member of the Anonymous and LulzSec online activist groups appeared in a London court Monday charged with hacking offences.

Security experts say Lulz Security (LulzSec) emerged from Anonymous, a hacker activist group which became well-known for targeting companies and institutions that opposed WikiLeaks and its founder Julian Assange.

Here is a timeline of hacking group LulzSec since May.

May 7 - Fox's "X Factor" contestant database breached.

May 10 - Fox.com sales database hacked and made public.

May 15 - LulzSec leaks details of hundreds of ATMs in Britain.

May 23 - Hacks Sonymusic.co.jp database.

May 30 - Defaces website of the U.S. Public Broadcasting System television network, posts fake article claiming deceased rapper Tupac is alive and living in New Zealand. LulzSec also leaks various databases from the PBS.org website.

June 2 - Leaks a number of databases the group said it stole from internal Sony websites and networks.

June 3 - Hacks into Federal Bureau of Investigation affiliate Infragard Atlanta and posts user database on LulzSec website, along with emails belonging to a group member.

June 6 - Publishes Sony BMG internal network maps and source code from the Sony Computer Entertainment Developer Network.

June 10 - LulzSec makes public 26,000 usernames and passwords for adult websites.

June 13 - Releases internal data from a U.S. Senate website after hacking its server. Also hacks the Web server of maker of online game Brink. LulzSec releases internal data and claims to have details of 200,000 Brink players.

June 16 - LulzSec claims responsibility for bringing down the public website of the Central Intelligence Agency. On the same day, the group releases 62,000 random email addresses and passwords without saying where they came from.

June 19 - Launches Operation Anti-Security -- the main aim is to steal and make public any sensitive government information including emails.

June 20 - Attacks website of British police Serious Organized Crime Unit (SOCA), temporarily making it inaccessible via the Web.

June 23 - Ryan Cleary is charged by British police, a day after he was arrested for recent attacks on websites. He is accused of attacking the SOCA website and sites owned by the British Phonographic Industry and the international Federation of the Phonographic Industry. LulzSec denied Cleary belongs to the group. The group did claim the attack on SOCA.

June 25 - LulzSec announces it is disbanding with one last data dump, which included internal AOL Inc and AT&T documents.

July 19 - Rupert Murdoch's British newspaper group, News International, tell staff to change passwords, after hackers attacked the website of his tabloid The Sun.

-- Hackers on July 25 redirected The Sun's online readers to a fake page which reported Murdoch was dead. LulzSec take responsibility in messages posted via the social networking site Twitter and say they are preparing more online assaults.

July 27 - British police arrest a teen-ager believed to be a leader of computer hacking groups. Police say the man, who goes by the hacker nickname "Topiary," is believed to have controlled the main Twitter account of LulzSec, which the group used to publish data obtained by hacking.

August 1 - Jake Davis, known as, "Topiary," appears in court charged with five offences. He is released on bail and will have no Internet access.