nod is a social media community powered by the open source social media platform, Mastodon. On Mastodon a post is known as a Toot. Every Mastodon community, known as an instance, is setup and administered independently with its own rules of conduct. Mastodon has no ads, and feeds are chronological and non-algorithmic.
There are thousands of Mastodon instances which form a network known as a federation. Any user on any instance in the federation may follow any other user on any instance; you only need signup to a single instance to follow users anywhere in the federation.