HO scale is a popular model railway scale that represents a ratio of 1:87. This means that one unit of measurement on the model corresponds to 87 units in real life. HO scale is widely used by hobbyists for building detailed train layouts and is compatible with a variety of accessories and scenery. The name "HO" stands for "Half O," indicating that it is half the size of the O scale, which has a ratio of 1:48. Due to its manageable size and availability of products, HO scale is favored by many model train enthusiasts, making it one of the most common scales in the hobby.