This is part of a series of lessons shared by Blueye at a local Geocaching 101 event.

Lesson 1: How does GPS Technology Work....

This question can be answered with so many different degrees of technical knowledge. My favorite overview of this is from How Stuff Works. This may get a little more technical that you are ready to handle, but it provides enough extra information to engage those who want to know a little bit more.

At the very basic level, the GPS (Global Positioning System) is a man made constellation of 27 satellites (24 active and 3 stand-bys), developed by the military, but made available to the public. The military, of course, has access to better information and more accurate signals. A GPS receiver allows you to obtain a high frequency, low powered radio signal from multiple satellites in order to establish a position. The number of satellite signals received will determine how accurate your positioning on the receiver will be. I'll leave the how and why for the advanced reading. Items that negatively impact the signal will negatively impact the accuracy of your positioning. Tree cover, electric wires, cloud cover, among other things will reduce accuracy.

The bottom line, is that with a GPS receiver, you know exactly where you are in the world. If you also know exactly where your destination is, then it will calculate how far you are from your destination. It can determine how fast you are traveling to your goal, and how reliable your signal is. It allows you to mark your current location so you can return to where you started. I'll get into more detail when discussing how to use the unit for Geocaching.

A longer read, but good introduction to beginners is Garmin's guide to GPS Basics.

The specific features of a GPS receiver will determine what you are capable of doing with the unit. Geocachers have their brand preferences, and they certainly have their opinions. Do your research and choose a product that makes sense for you.