In cybersecurity, 'supply' often refers to the 'supply chain,' which includes all the third-party vendors, software, and services that an organization relies on. A supply chain attack happens when hackers target these external suppliers to gain access to the main organization’s systems, often affecting many companies at once. Such attacks exploit trust relationships and can lead to widespread data breaches or system compromises. Protecting the supply chain is crucial, as vulnerabilities in even a single supplier can put the entire network at risk.