Nostr is 💯 a digital utility; a communication and identification protocol. Instead of identifying machines with IP addresses and people with e-mail adresses, you identify entities (real or virtual, human or machine) with keypairs. And instead of making webpages and uploading them to webservers, you make notes and upload them to relays. Social media is just one of endless use cases. This will eventually eat the Internet, basically.

Nostr is a protocol. Just like cables and outlets, amps and volts are a protocol for electricity.