Partialy reload my website Nginx? : I am currently working on the development of a platform and I was wondering how sites like Behance, Artsation and upwork do to partially reload their page. (When you click on a link, the page loads well but the menu does not move just like the footer). I first thought of Nginx but Artsation does not seem to be used Nginx.
I would like to know the things to reproduce this kind of loading page if someone could enlighten me on the subject.

Thanks