Rails-to-trails conservancy is a group of people who like to turn old train tracks into paths you can walk or bike on. Let's say there are some old train tracks that aren't used anymore, and nobody wants to use them for trains. That's where the Rails-to-trails conservancy comes in! They take the train tracks and make a path for people to walk or bike on, called a rail-trail. It's like making a long, skinny park with a special use, just for people to enjoy the outdoors. This also helps the environment, because people can get around without using cars or other vehicles that might pollute the air. So, the Rails-to-trails conservancy is a group of people who want to create fun, safe, and eco-friendly places for everyone to enjoy!