One of the many abilities of the Messages app is to share your location with others from your iPhone or iPad. To do this, tap the down arrow next to your contacts name, then tap the "info" button in the top right corner of the conversation screen. Here there are two options: "Send My Current Location" and "Share My Location." The first will send your location at that instant. The recipient(s) will see a map with your location tagged.
"Share My Location" will let the recipient follow your movement for a period of time that you designate, an hour, the rest of the day or indefinitely. To stop sharing, simply go back to Details and the option will be "Stop Sharing My Location."