NMAP is an open source tool for network exploration.
In a nutshell, NMAP performs host discovery, port scanning, operating system detection, and now application discovery.
In terms that we care about, NMAP provides us with a set of characteristics that describe a given host.
Characteristics are unordered, i.e. that the order in which open ports on a given host are listed provides no real information, only the fact that they are either open or closed.
INSERT NMAP SCAN COMMAND LINE
Because scan reports are in a plain textual format, all of the characteristics which we are interested in are parsed out.
INSERT NMAP SCAN REPORT AND INFO ON SECTIONS