By popular definition, mana is an omnipresent ether that can be drawn upon to construct magic spells. It is used in Magic: The Gathering and too-numerous-to-count role-playing games and fantasy stories. This Western understanding of mana can be attributed to Larry Niven, who first described it as such in his 1978 novella, The Magic Goes Away.3 Of course, Niven did not invent this perception of mana but probably combined the writings of early anthropologists with a bit of artistic license.
The anthropologist R.H. Codrington described mana as "an arbitrary, impersonal force possessed by people and objects"1 in his 1891 book, The Melanesians. This early work strongly influenced many anthropologists who linked Codrington's description of mana with many other culture's belief systems, including the Iroquois orenda, Sioux wakana, and Algonquian manitou.1 This association of mana with an all-pervading force resident in every aspect of being is inaccurate, but widespread nonetheless.
Mana describes a belief held and practiced by the people of Polynesiab and Melanesiac, and can be difficult to understand as "the idea of mana is not universal even in Melanesia, and the same term has much different meaning in neighboring Polynesia."1 It may be described as holiness, respect, or even virtue and is said to be exhibited strongly in people with great character. A Maorid chief would have a lot of mana, so much so that touching him was considered dangerous. Even so, mana was only experienced in fellowship whether between the chief and his village or even two men in a fight.2 In the case of the chief and his village, the shared mana would be dominated by the chief who represented the greatest force of mana; indeed that is why he is chief. Even when inanimate objects are said to have mana it is derived from people. Often an object was said to be imbued with an ancestor's mana.
1 www.allenvarney.com/av_mana.html
2 alexm.here.ru/mirrors/www.enteract.com/jwalz/Eliade/090.html
3 en.wikipedia.org/wiki/Mana
a Also referred to as Wakan Tanka
b Many Islands
c Black Islands
d New Zealand native word for their people, though often used to describe South Pacific natives in general