# MJML ```html Hello World ``` **becomes** ```html undefined
Hello World
``` ![/images/logo_mjml.png](/assets/logo_mjml.94cffb4896896048a65a426667b2fc699842265e12a41d8a9a094f16ad618277.a41383dd.png) MJML is a markup language designed to reduce the pain of coding a responsive email. Its semantic syntax makes it easy and straightforward and its rich standard components library speeds up your development time and lightens your email codebase. MJML's open-source engine generates high quality responsive HTML compliant with best practices. ![/images/mjml_screen.png](/assets/mjml_screen.8d670e92400adeb447f5775396ef7809cc711c20ae588e9c667f720f1b268c1a.a41383dd.png) Visit [mjml.io](https://mjml.io) for more details about this open source project initiated by the Mailjet development team. Find the mjml repository on [Github](https://github.com/mjmlio/mjml).