In some ways is similar to lemmy: it has groups (similar to Lemmy communities), decentralized usenet servers (each server chooses what groups want to host and serve to clients, and how much time to save attachments). Each post can have attachments like in emails.

There are other services acting as indexers. they are something like Google, you can search for files and you download them from the Usenet server.

Sorry for my poor explain, English is not my first language.