Activism, in a general sense, can be described as intentional action to bring about social or political change. This action is in support of, or opposition to, one side of an often controversial argument.

The word "activism" is often used synonymously with protest or dissent, but activism can stem from any number of political orientations and take a wide range of forms, from writing letters to newspapers or politicians, political campaigning, economic activism (such as boycotts or preferentially patronizing preferred businesses), rallies, blogging and street marches, strikes, or even guerrilla tactics. In the more confrontational cases, an activist may be called a freedom fighter by some, and a terrorist by others, depending on whether the commentator supports the activist's ends.

In some cases, activism has nothing to do with protest or confrontation: for instance, some religious, feminist or vegetarian/vegan activists try to persuade people to change their behavior directly, rather than persuade governments to change laws. The cooperative movement seeks to build new institutions which conform to cooperative principles, and generally does not lobby or protest politically.

wikipedia dixit