The backbone of web interactivity. JavaScript allows buttons to function, menus to open, and information to be loaded dynamically without reloading the page. With the rise of TypeScript, a superset of JavaScript, modern development gains robustness and scalability. It adds static typing, which is fundamental for building complex applications and ensuring code quality in large teams, making front-end development safer and more efficient. In addition to the browser, JavaScript (and, by extension, TypeScript) can run on the server thanks to Node.js, a runtime environment that extends its capabilities to the back-end. This makes JavaScript/TypeScript considered 'fullstack' languages, as they allow developers to use the same language to build both the user interface (front-end) and the server logic and interaction with databases (back-end). This language uniformity simplifies the development process, optimizes code and knowledge sharing between teams, and accelerates project delivery, making them powerful choices for modern applications.