Every base is just how you group powers of the radix. Binary groups by 2, octal by 8, hex by 16.
Why hex pairs with bytes
One byte = 8 bits = 256 values. Two hex digits cover exactly one byte (00–FF). That’s why memory dumps and colors use hex.
Octal today
Less common in web dev; still appears in Unix file permissions (chmod 755) — three bits per digit, three digits = nine bits… plus one implied — the mapping is historical but consistent once you learn the bit layout.
Quick conversion
From binary to hex: group bits from the right in fours, pad left. Each group is one hex digit. The reverse: expand each hex digit to four bits.