Dreamcatchers originated with the Ojibwe people and were later adopted by some neighboring nations through intermarriage and trade. It wasn't until the Pan-Indian Movement of the 1960 and 1970, that they were adopted by Native Americans of a number of different nations. Some consider the dreamcatcher a symbol of unity among the various Indian Nations, and a general symbol of identification with Native American or First Nations cultures.
The Ojibwe people have an ancient legend about the origin of the dreamcatcher. Storytellers speak of the Spider Woman, known as Asibikaashi; she took care of the children and the people on the land. Eventually, the Ojibwe Nation spread to the corners of North America and it became difficult for Asibikaashi to reach all the children. So the mothers and grandmothers would weave magical webs for the children, using willow hoops and sinew, or cordage made from plants. The dreamcatchers would filter out all bad dreams and only allow good thoughts to enter our mind. Once the sun rises, all bad dreams just disappear.
Traditionally, the Ojibwe construct dreamcatchers by tying sinew strands in a web around a small round or tear-shaped frame of willow (in a way roughly similar to their method for making snowshoe webbing). The resulting "dream-catcher", hung above the bed, is used as a charm to protect sleeping people, usually children, from nightmares.