Train Collecting is an exciting and fun and exciting hobby that usually begins with a train set and then continues with a train set and continues with a large collection of train cars, lots of track and very intricate layouts. There are several different sizes of trains (referred to as scales). Scales that very popular include G, HO, S, N, and Z. Certain countries or regions have train scales that are more popular than others. For example, HO scale is very popular in the United States while N scale, which has smaller cars, has more popularity in Japan.