Garmin Training Center is software that you use with your Garmin devices. Your Garmin device may be a simple Heart Rate Monitor (HRM) or complex Global Positioning System (GPS) based device, but the data captured by these devices is transferred to the Garmin Training Center, via the included Garmin® ANT Agent™. The data is also, optionally, transferred to GARMIN Connect, Garmin's online presence enabling you to further analyse your exercise data and share it with people around the world.
Take the simplest Garmin device as an example. Here an HRM will capture your workout data and when transferred to the Garmin Training Center via ANT transmitter will display the window as shown in Screenshot #1. There are 4 panes: 1. calendar (top left), 2. History of activities (bottom left), 3. Totals (top right) and 4. Graph (bottom right). The example shows a workout lasting for about 50mins with the max HR of 170bpm and the average HR of 153 bpm. With GPS you will also be able to see a Map of your route in the top right pane. The data uploaded to GARMIN Connect can be further analyzed and shared.