Hex Color
A hexadecimal color value is a text notation commonly used in CSS to represent RGB channel values.
Six-digit notation such as #f35120 uses two hexadecimal digits for red, green and blue. CSS also supports shortened and alpha-inclusive hexadecimal forms.
RGB color written as hexadecimal pairs
Six-digit notation such as #f35120 uses two hexadecimal digits for red, green and blue. CSS also supports shortened and alpha-inclusive hexadecimal forms. In practical terms, Hex Color belongs to the visual-production layer. Knowing that layer is important because it tells you what the term can change, what it cannot change, and where to look when something behaves unexpectedly.
Reading #f35120 as three channel values
#f35120 is a hexadecimal RGB notation: F3 red, 51 green and 20 blue.
Where hex notation appears in web design
You do not need to memorize the term in isolation. It becomes useful when you can recognize it in the tool, browser, file or conversation where the concept is doing real work.
A hex code says nothing about accessibility by itself
A hexadecimal color value is a text notation commonly used in CSS to represent RGB channel values. By contrast, RGB is an additive color model that represents colors with red, green and blue components. The two can appear in the same project, but they describe different parts of the work and should not be used as interchangeable labels.
The mistake: treating a color value as a contrast guarantee
The common mistake is to use Hex Color as if it also meant RGB. That blurs two separate decisions and usually sends troubleshooting in the wrong direction. A better test is practical: A hex value describes color channels, not whether the resulting foreground/background pair has sufficient accessibility contrast.
Why notation is only one part of color use
In day-to-day work, Hex Color matters when the concept needs to be identified precisely instead of being grouped with a nearby term. The practical value is not the vocabulary itself; it is being able to identify the right control, file, setting or decision when the concept becomes relevant.
#f35120 is a hexadecimal RGB notation: F3 red, 51 green and 20 blue. That example is useful because it turns the definition into something you can recognize, test and discuss with other people working on the same project.
Related terms worth learning next
Sources and further reading
Use these references when you need documentation-level detail, specifications or product-specific behavior beyond the plain-English explanation above.