Hex

Hexadecimal — base 16 — is how programmers read bytes. Each byte is two hex digits:

Analogy

Think of how we tell time. "A quarter past three" and "3:15" and "15:15" all describe the same moment — three different notations for one underlying fact. Hex is a different notation for the same byte: the value doesn't change, but the form is compact and tidy for humans reading hardware. It's the same reason chefs say "a pinch" while chemists say "0.3 grams" — same amount, different writing system for different audiences.

Hex dumps

A hex dump shows a blob of bytes with their offsets, the hex representation, and an ASCII gutter on the right showing printable characters.

Why two digits?

A byte is 8 bits. Hex digits are 4 bits each. So exactly two hex digits cover a byte with no wasted space. This is why hex became the default format for everything from MAC addresses to SHA-256 hashes to cryptographic keys.