Including black (#000000), there are 16,777,216 colours can be represented using hexadecimal format.
What is hexadecimal colour format?
Hexadecimal is the most common way to select colours in website designs.
The values are prefixed using a hash then followed by six hexadecimal digits.
The digits available are 0123456ABCDEF.
For example #000000 – black, #FFFFFF – white.
This provides more colours than our eyes as well as more colours than most, if not all, displays can distinguish between.