What does the red mean?

[v0031]

Even delicatessens whip up outstanding juices and smoothies, such as graviola, which comes from the spiky, green graviola fruit. It's a great thirst quencher on a hot day, subtle, not overly sweet, a kind of natural Squirt -- it's also a good digestive aid.

[v0031]

Can I ask you a question guy? How do you pick what color with which you highlight the words whose meaning you're unsure of? It used to always be red, but lately I've noticed you're mixing it up. I don't think you've ever done yellow before.

Yes, I never use the color yellow. I pick the color red as to raise your attention. But quite often I make  someone bored with my question, so I make a change.