A Single-Page Application (SPA) is a web application that loads a single HTML page and dynamically updates content as the user interacts with the app. Instead of loading entire new pages from the server, SPAs use JavaScript to rewrite the content of the current page. This approach provides a smoother, faster user experience similar to a desktop or mobile app.
SPAs rely heavily on JavaScript frameworks like React, Vue, or Angular to manage the user interface and handle routing within the app. When a user clicks a link or interacts with the page, the app fetches only the necessary data (usually via APIs) and updates the view accordingly, without reloading the whole page.
This model reduces server load and improves performance but also introduces challenges. SPAs can be harder to optimize for SEO, and initial load time may be longer since the full app must be downloaded up front. Proper implementation requires handling browser history, deep linking, and fallback for users without JavaScript.