Let’s collect links where one can learn more about features. It might make sense to ask permission to (re)use those and merge them into this package, in case the hosting sites go offline.
Multitouch/touchpads
Touchpad features, by Peter Hutterer:
→ https://who-t.blogspot.com/2010/06/incomplete-roundup-of-touchpad-features.html
What multitouch really is about, by Peter Hutterer:
→ https://who-t.blogspot.com/2010/10/thoughts-on-linux-multitouch.html