What is a byte, and why 255

Eight lights

Bit and byte

Each light is a bit, short for binary digit. Eight bits together make a byte, the unit computers use to keep a letter, part of a color or a piece of a photo.

Why 255, and not 256

Eight lights have 256 different combinations, from all off to all on. Since the first of them is zero, they go from 0 to 255.

Where 255 shows up

• Colors. On a screen, every color mixes red, green and blue, each from 0 to 255. White is 255, 255, 255.
• Internet addresses. An address like 192.168.0.1 is four bytes, each from 0 to 255.
• Old games. Many counters stopped at 255, because they were kept in a single byte.

Kilobyte, megabyte, gigabyte

A kilobyte is a thousand bytes; a megabyte, a million; a gigabyte, a billion. Sometimes 1,024 is used instead of a thousand, because 1,024 is a power of 2.

In Bytelight

In the game, two tiles join when they share no light. When you fill a whole byte, 255, the tile overloads and bursts into sparks.