The term tipster
refers to someone who on a regular basis provides information on likely winners in sporting events. In the past tips were bartered for and traded but in modern times, thanks largely to the Internet and premium rate telephone lines, it's increasingly likely that a tip will be sold.
Tipsters are often insiders of a particular sport able to provide bettors with information not publicly available. There are other tipsters who provide equally respectable results through analysis of commonly accessible information.
Tipster is also a UK slang term for a person who gives information regarding potential news stories, particularly those involving celebrities, to journalists.