Gatsby is a framework which uses React to build websites and apps. It is pretty much a framework on top of a framework. It allowed developers to create websites and apps that are much faster than if it was just built using React. Why are the websites that are built on Gatsby quicker? Well, when the website loads, Gatsby first loads only critical HTML, CSS, data and JS so that the end user would get the information much quicker then if they had to wait for all the components to completely load. After everything has loaded, Gatsby prefetches information for other pages of that website, so navigating around the site becomes a breeze.