What do all the fancy words in ads mean?

[Erik]

The phrase "zero stack" in the Agattu ad had me puzzled.

It turns out to be low-profile headset bearings, ie the ones for the steering.

www.cyclingnews.com news and analysis

 

[flecc]

The only ones I've ever come across personally are the conventional and increasingly popular threadless, and the others seem to be mainly for specialised sports bike use.

I can't help feeling that they are introduced as a way of getting higher profits from enthusiasts, and that many will quietly disappear and also cause headaches when spares are needed.
.