As it was first seen on the A30's keyboard, IBM introduced these 6 programmable circular keys for web navigation. Unfortunately, they were only available on the A3x series as no other model ever featured them again. This feature is not to be confused with the Easy Launch Buttons, despite their similarity with each other.
The keys are freely configurable, but their default purposes (as expressed by their labels) are:
See the How to get special keys to work page to know how to configure these keys.
Models featuring this technology