History of compensation... As the new millennium approached, professional athlete salaries exploded to unprecedented levels as multi-million dollar paychecks became the norm. But endorsements proved to be the most lucrative, as royalties earned players far more than their actual paychecks.

A decade after retiring from the NBA, basketball great Michael Jordan was making more than he did during his entire career with the Chicago Bulls. Endorsement deals from Nike earned the former player $100 million in royalties and his ownership stake in the NBA team Charlotte Hornets catapulted his net worth to over the $1billion. Currently considered the richest athlete of all time, Jordan wasn't the first athlete to join the billionaire boys club.

Since joining the PGA (Professional Golf Association) in 1996, golf legend Tiger Woods has earned a whopping 88% of his income from endorsement deals with Nike Golf, Upper Deck and Rolex. Woods was the first professional athlete to achieve the historic milestone in 2009 after reaching $1 billion in career earnings. And despite an off season in 2013, he was still the highest paid active athlete in the world, earning $78.1 million due to endorsement deals.

More tomorrow...