You can send a "Zap" or Lightning tip to anyone. To have it be counted as a Zap and not just another Lightning tip, the receiver needs to use one of the following wallets:

strike.army

vida.page

stacker.news

Bitcoin Jungle

ln.tips (LightningTipBot)

Geyser

Bitcoin Beach

Current (Client+Wallet)

Wallet of Satoshi

Zaps are just Lightning tips that are integrated to Nostr and are displayed on Nostr posts and profiles.