A grassroots movement (often referenced in the context of a political movement) is one driven by the constituents of a community. The term implies that the creation of the movement and the group supporting it is natural and spontaneous, highlighting the differences between this and a movement that is orchestrated by traditional power structures. Often, grassroots movements are at the local level, as many volunteers in the community give their time to support the local party, which can lead to helping the national party. For instance, a grassroots movement can lead to significant voter registration for a political party, which in turn helps the state and national parties.
Faking a grassroots movement is known as astroturfing. Astroturfing, as the name suggests, is named after AstroTurf, a brand of artificial grass. Astroturfing means to mimic a grassroots movement, with the powerful lobbyists behind the movement hiding their agenda by pretending to be individuals voicing their opinions. The term has incorporated itself into common speech.