A mod_rewrite developer works with Apache's mod_rewrite module, a powerful tool for URL rewriting. They manipulate URLs to make them user-friendly, enhance site navigation, improve SEO, and implement security measures. Their tasks involve creating and managing rewrite rules, handling redirections, and debugging. They must understand regular expressions and server variables to craft rules that guide the server's response to specific URL requests. The developer must also ensure that the rewritten URLs maintain the site's functionality and user experience. This role requires a deep understanding of server configuration, HTTP protocol, and web architecture.