How HTTP really works
Something EVERY Software Engineer must know about HTTP (Demo)
An instruction known as HTTP keep-alive, also known as HTTP persistent connection, enables a single TCP connection to stay open for a number of HTTP requests and responses.
HTTP connections automatically terminate after each request. When a user accesses your website, their browser must establish fresh connections in order to download each of the items that make up your web pages (such as graphics, JavaScript, and CSS stylesheets), which can result in lengthy page loads.