POP also stands for
Point of Presence - a term used in
telcos for designating their service points. POPs constitute Internet and telephone network exchanges, and as a result POPs are primrary elements of the
Internet backbone, and are also usually coupled with large
POTS telephone network exchanges.
POPs also represent an important factor in determining provisioning of large-scale Internet connectivity. xDSL can only be within a certain distance from a POP due to the nature of signal degredation. Also, in Australia the distance from a POP can determine the cost per kilometre for large scale Internet connections due to the necessity to run fibre-optic cable for long distances. Telstra and all other upstream providers base a calculated charge on excessively long distance from the nearest POP.
The density of POPs will determine how "switched on" a city or town is. Because the connectivity of towns and cities is usually based on telco installation of cabling, and because large cities also generate large amounts of content, there can often be between 10 to 20 POPs in a medium sized city, 1 per small town, and varying densities based on the population and requirements of a region.