In the context of digital marketing and website development, plugins are additional software components that integrate with a content management system (CMS) to add specific features or functionalities. For example, in WordPress, plugins can add SEO tools, social media integration, security enhancements, and more. They allow website owners to customize and enhance their sites without needing to write complex code. Plugins play a crucial role in building versatile, feature-rich websites, but must be used judiciously to avoid slowing down site performance.