OK this is pretty simple. Whatever button you press, a coded data stream or burst is created and transmitted to a discriminator that takes the info of that datastream or burst and says "If I get this command I will tell the CD player to select the next disc". The triggering of the change mechanism is a short duration pulse to activate a latch circuit etc. just te same as momentarily pushing the from panel button.

A touchtone phone pad generates a 2 tome pulse that is identified by a discriminator and says the if these 2 tones are read simultaneously, "I will turn this particular circuit."

By definition, a pulse is a sort duration change of state of some sort of switching or generating device.

The keyboard you are sitting at is using a matrix connection under the keys to generate ASCII codes when you MOMENTARILY depress a key. That is a short duration pulse. If you hit CNTRL B you toggle the screen on or off in Powerpoint. The same holds true from power switching. Unless there is a toggle, rocker, or rotary switch in the primary supply of a device, any non latching mechanical control (push button etc) remote data stream, etc is delivering a MOMENTARY "PULSE" to trigger the device to goggle on or off.