introduced NIP-30 Custom Emojis yesterday and many clients were quick to implement it: Nostter, Rabbit and Snort added support right away.
Check out these collections that you can use in your notes or any other nostr app that supports them
naddr1qvzqqqr4fcpzpn2q3f5ucmrn0js6wmhu873y03k220kgqlmw0j2hg9jpv3uhaqtzqqy4x42nfpy4j42tfy7vqccf
naddr1qvzqqqr4fcpzqla9dawkjc4trc7dgf88trpsq2uxvhmmpkxua607nc5g6a634sv5qqr85ctsd4sku0mhnvx