Who is Carl Icahn, and why does he want to buy Dell?

On monday, word spread that Carl Icahn has made a bid for Dell that could oust its founder and CEO Michael Dell from the company. But who is Icahn, and what does he want with Dell? Often described as an "activist investor," he's one of the world's richest men. He's made a name for himself over recent years with a series of high-profile investments. Just a few months ago, he bought a large share in Netflix with a view to sell the company, forcing the company's board to enact a "poison pill" plan ...