One of the major appeals of model railroading is making something that reflects your inner sense of aesthetics. Model train scenery is how this is done; anyone can make a model railroad that just goes around in a circle; it's that urge to set a scene, or tell a narrative, that makes model railroading such a compelling hobby and creative outlet. People who get into model railroading quickly get into the other aspects of the hobby, the modeling of terrain and other features.
Model trains scenery can be nearly anything, from small cars and tiny buildings set by the side of your tracks to more elaborate displays that model mountains, specific villages, even down to painting and placing individual trees. A few people in the hobby refer to it as their 'model train scenery habit', and talk about how they can't go to Michael's Craft Stores or Hobby Lobby without looking at something as a potential basis for scratch building a new piece of terrain, or a new building.
And that brings us to the first question. If you're getting into model train scenery, do you want to buy premade terrain, or make your own? Buying pre-made is simpler, and easier, and a lot of people who get into modeling with their train setups, start out with pre-made scenery. Pre-bought is a good way to put in your foundational scenery, particularly since the National Model Railroading Association (NMRA) makes solid guidelines on both interoperation of components (linking cars to locomotives, making sure that everyone's locomotives work on everyone else's track) and on dimensions and scales. This means that if you get NMRA-certified terrain in the scale you model at, everything will be pretty close.
On the other hand, there are entire sub-genres of model trains scenery that don't have commercial niches; these are settings and themes that aren't as popular, and nobody can make enough money to pay for the sculpting needed to bring them into production. This isn't the end of the world; it's a doorway to creativity. It's surprising how many common household items can be turned into H, HO or N scale scenery with an Exacto knife and a bit of time and patience; indeed, for a lot of model railroading aficionados, time spent at the workbench is the most enjoyable part of the hobby.
Most model railroaders do a mixture of pre-bought and self made model train scenery; they focus on what time period or theme they enjoy doing, and slowly and gradually collect (or make) the pieces of terrain that they enjoy. It also becomes a way to bond with other model railroaders, and to bond with their children, who often get their first taste of the hobby by helping Mom or Dad glue something together, and then slowly put together the diorama and run the trains on the rails, to get everything going, and to see something that grew from their own hands and their own minds, made real.
