The Apple Pro Keyboard was released in 2000 and replaced the Apple USB keyboard that was first released with the original iMac. The 109-key Apple Pro Keyboard had a completely transparent case with dark gray translucent keys. Notably, this keyboard removed the power key which had been present on Macintosh keyboards since 1987.
The design of the keyboard returned to the earlier extended-keyboard design last used in the Apple Extended Keyboard II. Like its predecessor, the Apple Pro Keyboard used a single support leg spanning the entire width of the keyboard to slightly elevate the back of the keyboard. When the iMac G4 was released in 2002, an Apple Pro Keyboard with the same design was released with opaque white keys.
As of 2020 Apple has released approximately 20 external keyboard designs. In general, Apple Macintosh keyboards are different from standard keyboards because they include a Command key (⌘) for shortcuts; an Option key (⌥) for entering diacritical marks and special characters; and a Help or fn (function) key. Earlier Apple keyboards also included a power key (◁), while newer keyboards include eject (⏏).
Source: Wikipedia
