What is SPA (Single page application) in AngularJS?

Single-Page Applications (SPAs) are web applications that load a single HTML page and dynamically update that page as the user interacts with the app. SPAs use AJAX and HTML to create fluid and responsive web apps, without constant page reloads. However, this means much of the work happens on the client side, in JavaScript.

A single HTML page here means UI response page from the server. The source can be ASP, ASP.NET, ASP.NET MVC, JSP and so on.

A single-page web application, however, is delivered as one page to the browser and typically does not require the page to be reloaded as the user navigates to various parts of the application. This results in faster navigation, more efficient network transfers, and better overall performance for the end user.