(covers information from several alternate timelines)
A protest, also known as a demonstration, is an act by a person or group to show opposition or support to a cause.
In 2024, an attempt to organize a rally in protest of the treatment of Homeless in the Sanctuary District in San Francisco instead turned into the Bell Riots. (DS9: "Past Tense, Part I", "Past Tense, Part II")
Protests were held on the Torothan homeworld after the caste system was abandoned but those disadvantaged by it found little had changed. Ultimately protests and court action were abandoned in favor of terrorism. (ENT: "Desert Crossing")
In 2374 Bajoran Vedek Yassim announced that she would put on a demonstration against the Dominion and the evil it represented. An attempt by Major Kira Nerys to dissuade her from doing so failed, and the event went forward. The event shocked Kira and other witnesses, as Yassim committed suicide by hanging on the Promenade, while saying "Evil must be opposed." (DS9: "Rocks and Shoals")
In an alternate reality in 2371, Makull and his supporters of an unknown species performed a demonstration against polaric ion energy in front of a polaric ion power plant. This demonstration led to Kathryn Janeway getting injured after accidentally getting involved. Protests against polaric energy also occurred in Kalto Province. (VOY: "Time and Again").