A hacker is a person who breaks into computers and computer networks for profit, in protest, or because they are motivated by the challenge. Anonymous broadly represents the concept of any and all people as an unnamed collective.
We [Anonymous] just happen to be a group of people on the internet who need — just kind of an outlet to do as we wish, that we wouldn't be able to do in regular society. ...That's more or less the point of it. Do as you wish. ... There's a common phrase: 'we are doing it for the lulz.'
Trent Peacock. Search Engine: The face of Anonymous, February 7, 2008.
Their Operations in 2011;
1.2011 Wisconsin protests
On February 27, 2011, Anonymous announced a new attack on Koch Industries as a response to the Wisconsin protests. Between 1997 and 2008, David and Charles Koch collectively gave more than $17 million to groups, such as Americans for Prosperity, Club for Growth and Citizens United, lobbying against unions (but also gave ten times as much to non political charities and non-profits over that same time). The Kochs are one of (Republican) Governor Walker's largest corporate supporters. Anonymous accused the brothers of attempting "to usurp American Democracy" and called for a boycott of all Koch Industries products.2.Operation Sony
Anonymous announced their intent to attack Sony websites in response to Sony's lawsuit against George Hotz and, specifically due to Sony's gaining access to the IP addresses of all the people who visited George Hortz' blog as part of the libel action, terming it an 'offensive against free speech and internet freedom'. Although Anonymous admitted responsibility to subsequent attacks on the Sony websites, Anonymous branch AnonOps denied that they were the cause behind a major outage of the Playstation Network in April 2011. However as Anonymous is a leaderless organisation, the possibility remains that another branch of the group is responsible for the outage. The hacker group Lulzsec has taken credit for the PSN outage.3.Spanish Police
On June 12, 2011, there was a DDoS attack on the website of the Spanish Police, starting at 21:30 GMT. Anonymous claimed responsibility the following day, stating that the attack was a "direct response to the Friday arrests of three individuals alleged to be associated with acts of cyber civil disobedience attributed to Anonymous." www.policia.es was down for aproximately an hour as a result of their efforts.
4.Operation Malaysia
The Anonymous group was trying to express their anger since Malaysia's Government blocked a few file sharing websites for breaching the Copyright Act 1987.
In total, MCMC’s Network Security Centre detected service outages to 91 websites, 51 of which are Government-related websites. Out of the 91 websites, 76 have been recovered, so far with work continuing to achieve speedy recovery as soon as possible. Typically, if a website has been hacked, website administrators would have to evaluate the damage caused by the attack and then proceed to restore access to the website. In most cases, strengthening of the security measures will also be part of the process. As of 4.00pm this afternoon, most Government-related websites are accessible to the public and have either not been affected by the service outages or have recovered from the attacks.
**Ask yourself why these websites seemed "very easy" to be attacked even though they have been warned 2 days earlier before the operation?
(Source referred from Wikipedia and BERNAMA)
