Why are some threads highlighted in yellow?

[Joshua Randall]

Why are some threads highlighted in yellow? I'm sure the answer is going to be something obvious and I'll feel stupid for asking, but at my age, I'm just glad I still remember the question I started with.

 

[Morrus]

Wiki threads.

 

[Li Shenron]

Maybe it's just me but my mind tend to "not see" those yellow thread at all, it just skips them...

 

[Joshua Randall]

I thought they were advertisements at first, and skipped over them, too.