A potlatch is a gift-giving feast practiced by Indigenous peoples of the Pacific Northwest Coast of Canada and the United States, among whom it is traditionally the primary governmental institution, legislative body, and economic system. This includes the Heiltsuk, Haida, Nuxalk, Tlingit, Makah, Tsimshian, Nuu-chah-nulth, Kwakwaka'wakw, and Coast Salish cultures. Potlatches are also a common feature of the peoples of the Interior and of the Subarctic adjoining the Northwest Coast, although mostly without the elaborate ritual and gift-giving economy of the coastal peoples (see Athabaskan potlatch).

A potlatch involves giving away or destroying wealth or valuable items in order to demonstrate a leader's wealth and power. Potlatches are also focused on the reaffirmation of family, clan, and international connections, and the human connection with the supernatural world. Potlatch also serves as a strict resource management regime, where coastal peoples discuss, negotiate, and affirm rights to and uses of specific territories and resources. Potlatches often involve music, dancing, singing, storytelling, making speeches, and often joking and games. The honouring of the supernatural and the recitation of oral histories are a central part of many potlatches.

From 1885 to 1951, the Government of Canada criminalized potlatches. However, the practice persisted underground despite the risk of government reprisals including mandatory jail sentences of at least two months; the practice has also been studied by many anthropologists. Since the practice was decriminalized in 1951, the potlatch has re-emerged in some communities. In many it is still the bedrock of Indigenous governance, as in the Haida Nation, which has rooted its democracy in potlatch law.

The word comes from the Chinook Jargon, meaning "to give away" or "a gift"; originally from the Nuu-chah-nulth word paɬaˑč, to make a ceremonial gift in a potlatch.

A potlatch was held on the occasion of births, deaths, adoptions, weddings, and other major events. Typically the potlatch was practiced more in the winter seasons as historically the warmer months were for procuring wealth for the family, clan, or village, then coming home and sharing that with neighbors and friends. The event was hosted by a numaym, or 'House', in Kwakwaka'wakw culture. A numaym was a complex cognatic kin group usually headed by aristocrats, but including commoners and occasional slaves. It had about one hundred members and several would be grouped together into a nation. The House drew its identity from its ancestral founder, usually a mythical animal who descended to earth and removed his animal mask, thus becoming human. The mask became a family heirloom passed from father to son along with the name of the ancestor himself. This made him the leader of the numaym, considered the living incarnation of the founder.

Only rich people could host a potlatch. Tribal slaves were not allowed to attend a potlatch as a host or a guest. In some instances, it was possible to have multiple hosts at one potlatch ceremony (although when this occurred the hosts generally tended to be from the same family). If a member of a nation had suffered an injury or indignity, hosting a potlatch could help to heal their tarnished reputation (or "cover his shame", as anthropologist H. G. Barnett worded it). The potlatch was the occasion on which titles associated with masks and other objects were "fastened on" to a new office holder. Two kinds of titles were transferred on these occasions. Firstly, each numaym had a number of named positions of ranked "seats" (which gave them a seat at potlatches) transferred within itself. These ranked titles granted rights to hunting, fishing and berrying territories. Secondly, there were a number of titles that would be passed between numayma, usually to in-laws, which included feast names that gave one a role in the Winter Ceremonial. Aristocrats felt safe giving these titles to their out-marrying daughter's children because this daughter and her children would later be rejoined with her natal numaym and the titles returned with them. Any one individual might have several "seats" which allowed them to sit, in rank order, according to their title, as the host displayed and distributed wealth and made speeches. Besides the transfer of titles at a potlatch, the event was given "weight" by the distribution of other less important objects such as Chilkat blankets, animal skins (later Hudson Bay blankets) and ornamental "coppers". It is the distribution of large numbers of Hudson Bay blankets, and the destruction of valued coppers that first drew government attention (and censure) to the potlatch. On occasion, preserved food was also given as a gift during a potlatch ceremony. Gifts known as sta-bigs consisted of preserved food that was wrapped in a mat or contained in a storage basket.

Dorothy Johansen describes the dynamic: "In the potlatch, the host in effect challenged a guest chieftain to exceed him in his 'power' to give away or to destroy goods. If the guest did not return 100 percent on the gifts received and destroy even more wealth in a bigger and better bonfire, he and his people lost face and so his 'power' was diminished." Hierarchical relations within and between clans, villages, and nations, were observed and reinforced through the distribution or sometimes destruction of wealth, dance performances, and other ceremonies. The status of any given family is raised not by who has the most resources, but by who distributes the most resources. The hosts demonstrate their wealth and prominence through giving away goods.

Potlatch ceremonies were also used as coming-of-age rituals. When children were born, they would be given their first name at the time of their birth (which was usually associated with the location of their birthplace). About a year later, the child's family would hold a potlatch and give gifts to the guests in attendance on behalf of the child. During this potlatch, the family would give the child their second name. Once the child reached about 12 years of age, they were expected to hold a potlatch of their own by giving out small gifts that they had collected to their family and people, at which point they would be able to receive their third name.