nXhtml is an addon for Emacs mainly for web development. Two main parts of it are nxhtml-mode (based on nxml-mode) for editing XHTML and MuMaMo for multiple major modes in an Emacs buffer. The XHTML editing comes with completion and instant validation. MuMaMo makes it possible to edit template files like PHP which contains a mix of programming language with the full support of the corresponding Emacs major modes for those languages.