Communication is Key
Have you ever become separated from a friend while in a crowd? If so, you know the challenge of searching for someone when surrounded by thousands of other people. If you and your friend have cell phones, your chances of finding each other are good. A cell phone's ability to send and receive messages makes it an ideal communication device.
Source
Boundless vets and curates high-quality, openly licensed content from around the Internet. This particular resource used the following sources:
"OpenStax College, Introduction. October 16, 2013."
http://cnx.org/content/m44450/latest/Figure_09_01_00.jpg
OpenStax CNX
CC BY 3.0.
