Dr. Christopher Sibona , a PhD student in the Computer Science and Information Systems program at the University of Colorado Denver Business School has found that frequent, unimportant posts on Facebook is the number reason for ‘unfriending’, a term described as the ending of online friendship.

Sibona surveyed more than 1,500 Facebook users on Twitter to know how friendships online end in order to help develop a ‘theory of the entire cycle of friending and unfriending’.

Unfriending occurs when online relationships turn sour. New Oxford American Dictionary has chosen the world 'unfriending' as its 2009 Word of the Year. It defines the word as 'To remove someone as a "friend" on a social networking site such as Facebook.

The second reason for Facebook unfriending was posting about polarizing topics like religion and politics. "They say not to talk about religion or politics at office parties and the same thing is true online," he said. The inappropriate posts, such as crude or racist comments were on third.

He also noticed a hierarchy of dominant and subordinate relationships among users. He found that those sending a friend request have the chances of being unfriended while those unfriending appear to be dominant in a relationship.

He observed that the etiquettes online were different from those face to face. "There is a lot more nuance in the offline friendship world. You don't have to go up to someone and ask them to be your friend. That's not the case online. It can be awkward," said Sibona.

He found some users very hurt at being unfriended while others were more amused. His survey found that 57 percent of the respondents unfriended for online reasons compared to 26.9 percent did that for offline behavior.