Brian Karis has shared an extensive breakdown of UE5's Nanite tool at SIGGRAPH 2021.
Unreal Engine 5 has been out for less than half a year but many artists already use it to simplify their workflows. One of the tools that help the artists the most is Nanite, UE5's new virtualized geometry system which uses a new internal mesh format and rendering technology to render pixel scale detail and high object counts. It intelligently does work on only the detail that can be perceived and no more. Nanite's data format is also highly compressed and supports fine-grained streaming with an automatic level of detail.
To show people what Nanite is capable of, an Engineering Fellow at Epic Games Brian Karis released a 155-pages-long document that explains literally everything there is to explain about the tool. How and why it was created, what it is able to do, what tasks can be accomplished with it, the tool's future, etc. We definitely recommend reading the entirety of the document if you want to learn more about Nanite. It can be accessed by clicking this link.