These charted "jet" routes (there are also V-Victor airways at lower altitudes) connect various navigation aids around the world. They used to be between NDB (non directional beacons--like radio stations putting out a signal) and VORs (very high frequency omnidirectional receivers), but are more and more relying on GPS designated intersections.
Pilots usually use paper "maps" to navigate their way around (given permission by Air Traffic Controllers of course), produced by Jeppesen.
Jeppesen (formerly Jeppesen Sanderson, and still used today) is an American company that specialises in aeronautical charting and navigation services, flight planning, pilot supplies and aviation training. The company is a subsidiary of Boeing Commercial Airplanes. Jeppesen also publishes related software, some of which is used on its electronic flight bag product line.I can't readily find a picture on the net of the charts to show you what they look like. Let me know if you'd like me to get a hold of one and scan it so you can see what they look like....
The company was founded in 1934 by Elrey Borge Jeppesen, a pilot himself working for Varney Airlines, who was the first to make aeronautical charts for pilots to navigate in flight. The information he collected and the charts he drew were at first only for personal use, but fellow pilots quickly saw the benefits of using these charts and
Jeppesen started selling copies of his chart book for 10 dollars. Other pilots started to collect data on their own routes and handing this to Jeppesen for him to include in his navigation book.
United Airlines, the airline Jeppesen worked for in the late 1930s after Varney airlines had merged with several other companies to form United Airlines, was one of the first airlines to start using Jeppesen's charts. After a while the chart business started taking up so much of Jeppesen's time that he quit his job as a Captain and became dedicated to making charts.