The Air New Zealand NPC is New Zealand's premier domestic competition generally played between August and October every year. Twenty seven teams, each representing a provincial union, make up the competition across three divisions.

New Zealand's provincial unions are (from north to south): Northland, North Harbour, Auckland, Counties Manukau, Thames Valley, Waikato, Bay of Plenty, East Coast, Poverty Bay, Hawke's Bay, King Country, Taranaki, Manawatu, Wanganui, Waiararapa-Bush, Horowhenua-Kapiti, Wellington, Nelson Bays, Marlborough, Buller, West Coast, Canterbury, Mid Canterbury, South Canterbury, North Otago, Otago and Southland.

The style of rugby differs as you travel around the country.

South Island teams tend to base their game around the forwards, mainly because of wet, heavy grounds. Teams in the North Island are better known for their expansive play with conditions more suited to running rugby.

Some of the more remote unions, like the East and West Coasts, are famous for unique and free-spirited styles all of their own.

The NPC has been contested since 1976, but has changed in format several times since then. In the first year, Division One comprised seven North Island teams and four from the South Island, with the remaining provinces contesting a split second division, where South Island teams played each other and North Island teams did the same.

The lowest-placed Division One team (South Island) played the winner of Division Two (South Island) in a promotion / relegation battle, thus keeping four South Island teams in Division One.

The lowest-placed Division One side (North Island) was automatically relegated, and the winner of Division Two (North Island) was automatically promoted. But Taranaki found in 1979 that they were relegated after finishing ahead of three South Island teams.

The format continued until 1985 when Division Three was introduced, split between islands in the same way. The bottom-placed team was relegated automatically from Divisions One and Two, and the winner of Division Two was automatically promoted.

The two winners from each island section of Division Three played off for promotion, which led to North Harbour's promotion to Division Two only a year after the union was formed.

At the end of 1991 three Division One teams were relegated to make the total number of teams in each division equal at nine. From 1992 until now there have been semi-finals and a final to determine the winners of each division.

The only change came in 1998 when 10 teams were introduced in Division One and by doing so eliminating the need for byes.

Bay of Plenty won the NPC Division One title in 1976 but have enjoyed no success since then. Canterbury won the following year, and again in 1983 and 1997. Wellington took the title in 1978 and 1981, and Counties Manukau won for - to date - the only time in 1979.

Manawatu got their only title in 1980 and Waikato in 1992. Otago have won the title twice - in 1991 and 1998. And apart from that it has been all Auckland, winning in 1982, 1984 and 1985, four times in a row from 1987 - 1990, another four times consecutively from 1993-1996, and brilliantly in 1999, 2002 and 2003.

Alongside the provincial competition, and often between teams from different divisions, another battle takes place. In 1902 the governor of New Zealand, the fifth Earl of Ranfurly presented a trophy shield to Auckland, who were undefeated in provincial competition that year.

The Shield has since become known as the Ranfurly Shield, or Log of Wood, and is played for when the holders accept challenges from other unions, scheduling home games to defend it.

The significance of the Shield is immense. Just to play for it, no matter whether your team wins the challenge or loses by a big margin, is regarded as a huge privilege.

The fervour and festival atmosphere of the clashes is legendary, and the celebrations that have marked successful challenges by underdog lower division sides are remembered as red-letter days by those provinces for decades to come.

Lowly Marlborough upset Canterbury in the first challenge of 1973, and then put it up in Blenheim against all-comers for seven straight games before South Canterbury took it to Timaru, albeit briefly.

Every year, along with more fancied sides, Division Two and Three sides have an opportunity to challenge for the Shield. It's a big occasion for both players and supporters.