A Twitter Card is a feature that allows users to attach rich media, such as images, videos, and other content, to their tweets. This enhances the visibility and engagement of tweets by providing more context and information. There are different types of Twitter Cards, including Summary, Summary with Large Image, and Player Cards, each serving a unique purpose. To use Twitter Cards, developers need to add specific meta tags to their website's HTML. Once set up, when a link is shared on Twitter, the card will automatically generate, making the tweet more appealing. This feature is beneficial for businesses and content creators looking to increase their reach on the platform.