In the Beginning
According to legend, the history of the game of rugby hails back to the town of Rugby in England in 1823, when William Webb Ellis picked up a football and ran with it during a local game. The advent of the oval shaped ball used in rugby football formed a distinction from football (soccer) that has endured since. The game grew in popularity in Great Britain through club rugby and soon, rugby union internationals were played between the Home Unions (England, Ireland, Scotland and Wales), which would later grow into the Six Nations competition as it is today, including France and Italy.
The British Empire colonization introduced rugby in colonial territories throughout the British Commonwealth. By the early 1900s test matches were played between Southern Hemisphere and Northern Hemisphere nations, fostering relations between them. The arrival of professional 13-man rugby league in various countries in the early 1900s violated the strict amateur code of rugby union, and many players were lost to the rival code. However, the International Rugby Board (IRB) controlled 15-man rugby union has enjoyed dominance.
Evolvement of Worldwide Popularity
Undoubtedly, New Zealand, South Africa and Australia established themselves as the dominant rugby powers by the Second World War, and post war years saw an increase in international tours to strengthen the game, with stronger inclusion of the less powerful rugby nations like Argentina, Japan and the Pacific Island nations of Samoa, Fiji and Tonga. By the 1980s moves were afoot for a regular world championship, and the inaugural 1987 Rugby World Cup played in Australia and New Zealand spurred on the professional era of rugby union.
The history of the game of rugby would never be the same. The Southern Hemisphere Tri Nations competition between Australia, New Zealand and South Africa was introduced in 1996, along with the international regional Super 12 competition between the countries, which has since expanded to become the Super 15 in 2011. Similarly, the Northern Hemisphere international regional Heineken Cup was established. In addition, 7-aside rugby (Sevens) has become popular, with the IRB Sevens World Series and the Rugby World Cup Sevens allowing the smaller rugby nations to compete on more equal footing with super powers.
You can follow all recent developments and find more details on sites that specialize in sports and rugby in particular like NBC Sports, Ufakick, ESPN, and others.