UTF-8

Unicode Transformation Format - 8-bit

UTF-8 Bytes

UTF-8 bytes contain header bytes that tell the decoder how many bytes to read to get the character. It will be the first byte of the character.

F0 is 11110000, which is a header byte that says "this character needs 4 bytes" (because of the 4 1's)

Unicode Emojis

Unicode characters are typically used in hexadecimal format.
The most common emojis start with 1F6. i.e., 0x1F643 is the upside-down face 🙃 emoji.