Why did Tom Riddle change his name to Lord Voldemort?

Tom Marvolo Riddle was a Slytherin Half-Blood who would later be known as Lord Voldemort. He didn't want to keep his muggle father's name (Riddle) (Muggle; non-magical person) so he fashioned a new name out of the letters in his birth name.

Tom Marvolo Riddle is an anagram of I am Lord Voldemort.