> The Kwakwaka'wakw continue the practice of potlatch. Illustrated here is Wawadit'la in Thunderbird Park, Victoria, BC, (aka Mungo Martin House) a Kwakwaka'wakw "big house" built by Chief Mungo Martin in 1953. Very wealthy, that is, prominent, hosts would have a longhouse specifically for potlatching and for housing guests.
A gift economy is a type of economic system in which goods and services are given without any explicit agreement for immediate or future quid pro quo. A gift economy emphasizes social or intangible rewards, such as karma, honor, or loyalty, for giving. In some cases, simultaneous or recursive giving serves to circulate and redistribute valuables within a community. This can be considered a form of reciprocal altruism. Sometimes there is an implicit expectation of the return of comparable goods or services, political support, or the gift being later passed on to a third party. 


No, not gift economy. Social exchange. People exchange without even consciously being aware. Barter is a conscious awareness of an exchange of like for like where the value of the two things being exchanged are seen as equal. The gift economy in western society is mostly a Christmas ritual at best where people exchange gifts, or Halloween where people give candy to kids.

People share knowledge because it's a way to gain more knowledge. If people decide never to share knowledge with others then they'll have a harder time getting more knowledge. 

References
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1.  http://www.newworldencyclopedia.org/entry/Gift_economy
2. https://en.wikipedia.org/wiki/Gift_economy