Understanding URL

Uniform Resource Locator or URL is used by applications - often web browsers (Chrome, Edge, Firefox, Brave, etc.) - to access resources published to the Internet. URL is address to specific resource or functionality provided by web server applications (IIS, NGinx, Apache, etc.) or application integrated web servers (Node.js + Express, etc.). URL is used when web browser - or indeed any application - sends HTTP Request (oh which there are 4 main types: GET, PUT, POST, DELETE) to web server which sends back HTTP Response that indicates if operation succeeded or not and returns data requested by HTTP Request.

It is often thought that URL reads a specific file on web server, but this is simplistic and superficial view of the matter, because Paths and Query Parameters included within URL are abstractions to functionalities of application that is listening to TCP Port specified within URL. These functionalities of course might return a specific file on web server, but they might also be functionalities that create, update, search, read or delete data or trigger other programming logic on web server. It is common that when web browser loads resources from web server by sending HTTP GET Request that when resource - for example HTML page - is loaded then 30 more HTTP GET Requests are sent to load other content (CSS, JavaScript, Images, etc.) that is required to show HTML page correctly.