What is JavaScript primarily used for in web development?

JavaScript is primarily used as a programming language that enables interactive web pages, which is why this answer is the most accurate. It allows developers to create dynamic content that responds to user actions, such as clicking buttons, submitting forms, or hovering over elements. This interactivity is crucial for modern web applications, as it enhances user experience and engagement.

JavaScript runs on the client side in the browser, meaning it can respond to user input without needing to communicate with the server, making web pages feel more responsive and alive. Common uses of JavaScript include form validation, animations, and asynchronous requests to update web content without refreshing the page, all of which are essential features for creating contemporary web experiences.

The other options, while relevant to web development, describe different aspects. A database management tool is more related to back-end development, dealing with data storage and retrieval. A markup language, such as HTML, is used for structuring content on web pages but does not enable interactivity on its own. Finally, a styling language like CSS is responsible for visual presentation and layout of web content, rather than adding dynamic behavior.