Mark and space

Mark and Space are terms used in telecommunications to describe the two states of a signal. Think of it like a light switch: when the switch is turned on, the light is in the "on" state (or the "mark" state, in telecommunications terms). When the switch is turned off, the light is in the "off" state (or the "space" state).

Similarly, in telecommunications, we use a mark to indicate the presence of a signal and a space to indicate the absence of a signal. For example, in Morse code (a system of sending messages using short and long signals), a short signal is a mark and a long signal is a space.

When we transmit data over a telecommunication channel (like a phone line), we use marks and spaces to represent different pieces of information. This is called encoding. For example, in binary encoding, we use a high voltage to represent a mark and a low voltage to represent a space.

So, in essence, mark and space are just two different states of a signal that we use to transmit information.