What is highlight.js?

Highlight.js is a JavaScript library that adds syntax highlighting to code blocks on web pages, meaning it colors different parts of code (keywords, strings, comments, function names) so the code is easier to read visually. If you've ever read a technical blog post or documentation where code is displayed with colored text rather than plain black-on-white, that's likely syntax highlighting at work. What makes Highlight.js stand out is its automatic language detection: you can give it a block of code without specifying the programming language and it will usually figure out what language it is (Python, JavaScript, HTML, SQL, etc.) and apply the right color scheme. It supports over 180 languages out of the box. It has zero dependencies on other libraries, meaning you can add it to any webpage without worrying about compatibility conflicts. Using it is straightforward: include the library and a CSS theme file in your HTML, and add a single line of JavaScript to activate it on all code blocks in the page. It works both in the browser and on the server (via Node.js). You'd reach for Highlight.js when building a documentation site, a blog with code examples, a wiki, or any web page where you want to display code in a readable, styled way. It can be loaded from a CDN (a content delivery network, a fast cloud service) or installed via npm, the JavaScript package manager.