An activist is someone who takes action in support of or opposition to a cause.

Activism can take a range of forms, from writing letters to government representatives to organizing boycotts. Some activists engage in radical or even illegal activity to further their ends, while others prefer to stay within the boundaries of the law to win more supporters to their causes. Every time someone writes a letter to the editor, educates a friend about an issue, or phones an elected official, he or she is participating in activism.

People have been practicing activism for centuries with the goal of social and political change. Jesus Christ, for example, is considered an activist by some, thanks to His radical preaching and fearless approach to social reform. At various times in history, being an activist has been quite dangerous, as activism was equated with dangerous political dissent, making people who spoke out targets for persecution. At other times, activism has been tolerated or even encouraged.

On a lesser scale, activism might involve participating in activist causes, without actively organizing. Examples like participating in letter writing campaigns, phone banking for political candidates, walking in marches, and supporting boycotts and strikes are all examples of basic activism. Maybe activists start out at this level before moving on to more active organization, which involves things like leading marches, hosting organizing committees, community organizing, offering classes at teach-ins, and so forth.

In some instances, activism crosses the line of the law, as activists become swept up in the cause or feel that they have no other options. On the mild end of the spectrum, this might involve simple disobedience, such as refusing to clear a street after being ordered to do so by law enforcement. Others may pursue more violent tactics, which some people feel cross the line into terrorism. Many activist movements condemn violent activism, arguing that it reduces the strength of their cause and alienates potential converts.

Activists can organize for a wide number of causes. Political parties, the environment, social justice, and moral issues are all common rallying points for activists. Some people participate in activism because they have personally experienced injustice or prejudice, while others simply believe in the cause they support or oppose, regardless of personal experience.