babel-plugin-syntax-jsx enables parsing of JSX syntax in Babel. It's a foundational Babel plugin that doesn't transform JSX into JavaScript; it simply allows Babel to understand the syntax without throwing errors. This is essential for using other Babel plugins, like @babel/plugin-transform-react-jsx, which actually handle the JSX transformation. Including this syntax plugin is a prerequisite for any project utilizing JSX with Babel. Essentially, it prepares Babel to correctly interpret JSX before subsequent transformations occur.