Collections - A Collection is nothing more than a named Container to hold a group of your Items, for instance: "HO Scale Box Cars", or "Z Scale Engines". You can create as many Collections as you wish.
Containers - My Train Tracker uses two types of containers: Layouts and Collections. We only call them containers here in the documentation and we do so because they are what holds your individual Items, therefore making them containers.
Fields - Each Item in My Train Tracker is made up of a set of properties, or characteristics that describe your Item(s). These properties or characteristics are what we call "Fields". Ex: Title, Scale, Manufacturer, etc.
Items - An Item is any one specific piece of your train collection that you wish to document in My Train Tracker. It can be anything from a train engine to a caboose, or a building on your layout, a turn table, bridge, or a lighted tower. Any piece that you own and wish to document in My Train Tracker is considered an Item.
Layouts - A Layout in My Train Tracker represents one of your actual model railroad layouts. If you have multiple layouts, you can document each of them in a separate Layout container, or, if one or more of your layouts is quite large, you can break it down into idividual Layouts in My Train Tracker representing a certain section of your larger layout. Layouts are also Containers to hold individual Items representing the items that actually reside on that specific model layout.