|  | 5.1 | Most Common LAN Media
| 5.1.5 | Wireless communication

Wireless signals are electromagnetic waves, which can travel through the vacuum of outer space and through media such as air. Therefore, no physical medium is necessary for wireless signals, making them a very versatile way to build a network. Figure represents an electromagnetic wave.

Figure illustrates one of the most important charts in all of science and technology, the Electromagnetic Spectrum chart. You might be amazed that even tough all of the waves - power waves, radio waves, microwaves, Infrared light waves, visible light waves, ultraviolet light waves, x-rays, and gamma rays - look seemingly very different, they share some very important characteristics:

1. All of these waves have an energy pattern similar to that represented in Figure .
2. All of these waves travel at the speed of light, c = 299, 792, 458 meters per second, in vacuum. This speed might more accurately be called the speed of electromagnetic waves.
3. All of these waves obey the equation (frequency) x (wavelength) = c.
4. All of these waves will travel through vacuum, however, they have very different interactions with various materials.

The primary difference between the different electromagnetic waves is their frequency. Low frequency electromagnetic waves have a long wavelength (the distance from one peak to the next on the sine wave), while high frequency electromagnetic waves have a short wavelength.

The interactive calculator in Figure allows you to experiment. Try the interactive calculator by doing the following activities:

1. Enter a frequency and you will notice that the calculator displays the wavelength.
2. Enter a wavelength you will notice that the calculator displays the frequency.

In either case, the calculator display the electromagnetic wave associated with the calculation.

A common application of wireless data communication is for mobile use. Some examples of mobile use includes:

- people in cars or airplanes
- satellites
- remote space probes
- space shuttles and space stations
- anyone/anything/anywhere/anytime that requires network data
- communications, without having to rely on copper or optical fiber tethers

Another common application of wireless data communication is wireless LANs (WLANs), which are built in accordance with the IEEE 802.11 standards. WLANs typically use radio waves (for example, 902 MHz), microwaves (for example, 2.4 GHz), and Infrared waves (for example, 820 nanometers) for communication. Wireless technologies are a crucial part of the future of networking.