Hex
Binary you can actually read.
Where it came from
Hexadecimal (base 16) became standard in computing because one byte is exactly two hex digits: 8 bits = 2^8 = 256 = 16^2. That 1:1 mapping between nibbles and characters made it the natural way to "see" memory.
From debuggers dumping RAM to MAC addresses, hash outputs and color codes (#ff0000), hex is how machines show their innards to humans.
How it works
Digits 0–9 then A–F stand for 10–15. A byte like 255 is FF. Converting is grouping bits into 4-bit nibbles. Whitespace or "0x" prefixes are usually tolerated.
UWC encodes text to hex and decodes it back, and bridges hex with RGB so you can flip between #ff0000 and rgb(255,0,0) in the browser.