0.5.1 Hexadecimal Web Colors

You have already used hexadecimal as a compact way to represent binary values.

Web pages provide a familiar place where hexadecimal appears visually: color values.

A hexadecimal web color commonly uses six hexadecimal digits after a ## symbol.

For example:

#3366CC

The six digits are grouped into three pairs:

33 66 CC

Those pairs represent the red, green, and blue parts of the color.

Screens create many colors by combining different amounts of:

A six-digit hexadecimal color can be read as:

#RRGGBB

where:

Each pair ranges from hexadecimal:

00

through:

FF

That corresponds to decimal values from 0 through 255.

Consider:

#000000

The groups are:

Red   = 00
Green = 00
Blue  = 00

With all three components at zero, the result is black.

Now consider:

#FFFFFF

Each component is at its maximum hexadecimal value:

FF

The result is white.

A strong red value can be represented as:

#FF0000

That means:

Red   = FF
Green = 00
Blue  = 00

A strong green:

#00FF00

A strong blue:

#0000FF

The position of the hexadecimal pair matters.

The same symbols in a different position describe a different mixture.

Consider:

#FFFF00

The color contains maximum red and maximum green, with no blue.

That produces yellow.

Another example:

#00FFFF

contains green and blue at maximum values.

That produces cyan.

The goal is not to memorize a huge color chart.

The important idea is that one written hexadecimal value encodes three numeric color components.

Because one hexadecimal digit corresponds to four bits, one two-digit color component corresponds to eight bits.

For example:

FF

maps to:

11111111

and:

00

maps to:

00000000

So:

#FF0000

can be understood as three groups of eight bits:

11111111 00000000 00000000

The web color is another real example of hexadecimal acting as a shorter human-readable representation of binary-oriented information.

When a color appears in HTML or CSS, you may see:

#3366CC

The ## helps indicate that the following characters form a hexadecimal color value.

The hexadecimal digits themselves are:

3366CC

A small CSS example is:

h1 {
    color: #3366CC;
}

Read it as:

You do not need to master CSS yet.

For now, notice the connection:

hexadecimal representation → digital color → visible result on a webpage

These two values represent the same color:

#3366CC

and:

#3366cc

Hexadecimal digits A through F are not changed in value by letter case.

A project may still use one style consistently for readability.

You may encounter a three-digit form such as:

#36C

In CSS, this expands each digit:

#36C

to:

#3366CC

The six-digit form makes the red, green, and blue pairs easier to see while you are learning the representation.