CISA stands for the Cybersecurity and Infrastructure Security Agency, a U.S. government agency under the Department of Homeland Security. CISA is responsible for safeguarding the nation’s critical infrastructure from cyber threats, physical attacks, and other hazards. It works with government agencies, private companies, and the public to improve cybersecurity, share threat information, and respond to incidents. CISA also develops best practices, provides guidance, and coordinates national efforts to enhance the resilience and security of essential services such as energy, transportation, and communications.