What does the A refer to in motor home classes?

Motorhomes are generally grouped into three categories: Class A, Class B, and Class C. Class A motorhomes are usually the largest, sometimes as long as 40 feet. They are shaped either like buses, or else like huge boxes on wheels. Most have functioning 3-piece bathrooms (often a 4-piece) and a functioning kitchen, with stove and refrigerator. Many have 'slide-outs' which, when parked, provide greater 'living room' floor space. They usually have a separate bedroom as well. Furnaces are common. Brand new, many sell in the quarter million to half million dollar range. Class B motorhomes are the smallest type. The VW Westphalia is a Class B, as are some larger ones, up to the size of a Sprinter or a little bigger. Generally, they retain the shape of a van. Washroom facilities are rare, and cooking facilities are minimal. Class C motorhomes can often be longer than some Class A ones, and have most of the facilities as well, but are generally smaller. The biggest difference between Class A and Class C is the front of the vehicle: it retains the appearance of a truck. Class C motorhomes almost always have a sleeping compartment over top of the driving area. Slide-outs are not common. Many have limited washroom facilities, and some do not have a separate bedroom. Kitchen areas can be a little smaller, and 'living rooms' are small. Do a google search of "Class A" + 'Motorhome' to get an idea of the selection and features available.