Additional keys
The number of
additional keys provided in the design of the keyboard.
Such keys do not belong to the standard layout and are intended for quick access to specific functions or individual applications — for example, to control the media player or open mail with one click. This function is convenient because commands from additional keys are usually recognized by the system regardless of what is on the screen — thanks to this, for example, you do not have to close the text editor to switch tracks in the player.
Note that in this case we are talking about individual keys that have a strictly defined purpose and corresponding markings. Programmable buttons, the Fn key (see below) and the functions of the main keys implemented through Fn are not taken into account in this paragraph.
Fn key
The presence on the keyboard of the
Fn key(short for function). It belongs to modifiers, similar to Shift or Ctrl: by itself it does not perform any action, but when pressed simultaneously with another key, it changes its original purpose. Fn is often found in compact keyboards (see "Format"), but can also be set in full-sized ones. The features it provides include quickly changing the screen brightness or sound volume directly from the keyboard, using the centre keys as a Num-block, launching individual applications, and so on. Specific features of using the Fn key depend on the keyboard model.
Battery time
The operating time in this case is quite approximate: it is indicated for a certain average mode of use. The actual battery life may turn out to be either less or more than the claimed one, depending on the specifics of the application; in addition, the quality of a particular brand of batteries greatly affects the operating time. Nevertheless, this is a fairly reliable indicator, it is quite possible to evaluate different models and compare them with each other: the difference in the claimed operating time is usually quite consistent with the difference in real battery life when using batteries of similar quality.
It is worth saying that modern battery-powered keyboards have pretty solid battery life, measured in months; in the most "long-playing" models, the operating time is about 36 months (that is, 3 years).
Waterproof
Protecting the keyboard from spilling liquid on it. Most
waterproof keyboards do not have a full-fledged sealed case and are designed to remain operational in the event of accidental contact with a relatively small amount of liquid (up to 200 mL) — for example, in the classic case of spilling coffee on the keyboard.
