Binary numbers are used in computer code. A "bit" is short for binary digit.

Binary numbers are a Base 2 numbers system where there are two options:

1 means On or Present

0 means Off or Absent

Maths Fun - Computer Bytes

Computer bytes do not use decimal numbers (base-10 numbers). They use binary numbers (base-2 numbers). Because computers use binary numbers,
a "kilobyte" is not really a thousand bytes, but is 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 or 1,024 bytes.
Also, a "megabyte" is not a million bytes, but is 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2
× 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 or 1,048,576 bytes.
Write a kilobyte and a megabyte using indices of base 2.

Maths Fun - A Nerdy Joke

There are 10 kinds of people - those who can understand BINARY and those who can't!