The scripting language primarily used for web page interactivity is JavaScript. It runs in web browsers and can respond to clicks, validate forms, animate elements, update content, and communicate with servers without requiring a full page reload.
Brendan Eich created JavaScript at Netscape in 1995 for Navigator, during a period when most web pages were static documents built with HTML. The language was later standardized as ECMAScript, while “JavaScript” remained the name most developers and users recognize. Modern browser engines execute JavaScript and expose web APIs that let scripts interact with the Document Object Model, storage, networking, media, and other browser features.
JavaScript is often confused with Java because of its name, but they are separate languages with different histories and designs. Python and Ruby can also power web applications, especially on servers, but JavaScript is the main language executed directly in browsers for client-side behavior. It is also used outside browsers through runtimes such as Node.js, Deno, and Bun.