HTML is the language that is used to design web pages. HTML stands for HyperText Markup Language. In HTML, you can design your web page and add content. HTML is a markup language (not a programming language).
This cannot be done alone with HTML.
- Backend web development - This includes APIs and web servers. Node.js is the best example here.
- Mobile app development - This includes both Android and iOS. React Native is the best example here.
- Desktop app development - This includes Windows, OSX, and Linux. Electron.js powers a lot of popular apps - including VS Code, Slack and Discord.
- Internet of Things (IoT) - This includes everything from cars to coffee makers, can be powered with Node.js.
- Rockets - SpaceX used Chromium for rendering UI on their Dragon Flight mission. So it is very well running outside of Earth as well.