its to go to a section in that webpage, for example; https://siteurl.whatever/home/#home, there would need to be in the html code that has that section recongized, so when you enter this url it would automatically load the webpage on that url. though it is not sent to the server its just for the clientside. since it doesnt refresh the webpage. also it can be used to load different webpages without having to refresh the page everytime they switch, useful for apps like render or school applications.