Searching with Google or Apple Maps is very useful, but the hidden function of the compass just makes finding the right location easier. You set your compass and immediately see whether you are also heading in the right direction. Taking a wrong turn won't happen anytime soon.
As an Android user you only have access to Google Maps, iOS users can use both Google Maps and Apple Maps. These apps are not available for Windows Phone, but you can turn to Here Maps for a similar compass function.
When you start up Apple Maps, you will see an arrow at the bottom left of the screen. Once you click on this, you will see the location where you are. If you press this again, a compass will appear at the top right of the screen. A blue field of view also appears on the side that your iPhone is pointed at. If you hold the iPhone right in front of you, you can see which way you're going and taking a wrong turn is almost impossible.
The blue field of view shows exactly which way you are going.
For both Android smartphones and iPhones, the compass function in Google Maps works the same. When you open this app, your GPS on your smartphone must be turned on for Google to determine your location. If this is successful, press the arrow key at the bottom right of your screen. It will turn into a mini compass and the screen will zoom in on the map. You will see an arrow appear at the blue ball in the direction you are walking up. When you rotate, the image also rotates. You know exactly which way you're going.
Google Maps zooms in and rotates the image with you.