Grassroots movements challenge established political systems by mobilizing community members to advocate for change from the ground up. These movements typically arise in response to social injustices or unmet needs, aiming to amplify the voices of the underrepresented. By organizing protests, campaigns, and community outreach, grassroots efforts can influence public opinion and push for policy reforms. Their decentralized structure encourages broad participation, enabling diverse groups to unite in pursuing common goals and effecting change within the political landscape.