With over 50 forms of synesthesia, this condition represents one of the richest perceptual conditions known to science. Rather than a deficit, synesthesia describes an augmentation of a very particular sensory experience. For synesthetes with colored-sequence synesthesia (CSS), the letter ‘K’ is actually ‘K’, Saturday means something very different than just Saturday, and  pops into their head right before dialing my hometown area code. Notice that the color choices are specific. If you were to ask a synesthete the color of Saturday today and two weeks from today, the answer will be the same. This is an important feature of synesthesia, as the consistency and specificity of the colors can be used to verify true synesthetic associations.
One critical distinction to make here is that these colors are, in fact, just associations. I say ‘just’ to emphasize that synesthetes do not mistakenly see this text in different colors. Rather, the letters trigger an association of color, much like if I were to say Harry Potter, some image would pop into your head as an automatic association with the name. Nonetheless, you don’t see Harry Potter. You just have the latest movie trailer stuck in your head until I change the subject. This is what it is like to be a synesthete, except that you might have these automatic associations between letters and color, between taste and color, between music and shape, or between touch and texture.