HTML Web Storage API

Question

I'm currently working on the HTML5 Web Storage section and since I began lesson 1 of HTML this is the first time it feels like I am jumping into something new and advanced. I have a very basic understanding of cookies and why they are used but it feels like the lesson doesn't dig deeper into what API is or how it functions. Will it be discussed further in JavaScript and should I not worry about it now as much? Everything I've learned so far I have implemented into my personal website starting from scratch but this particular element of web storage I have not been able to do so.

*Also will this apply to my next upcoming lessons as well including Drag&Drop API and Geolocation API?