Delivery is the process of transporting goods from a source location to a predefined destination. Cargo (physical goods) is primarily delivered via roads and railroads on land, shipping lanes on the sea, and airline networks in the air. Certain types of goods may be delivered via specialized networks, such as pipelines for liquid goods, power grids for electrical power and computer networks such as the Internet or broadcast networks for electronic information. Car transport is a particular subgroup; a related variant is Autorack, which involves transport of autos by railroads. Delivery is a fundamental component of commerce and trade, and involves transport and distribution. The general process of delivering goods is known as distribution, while the study of effective processes for delivery and disposition of goods and personnel is called logistics. Firms specializing in delivering commercial goods from the point of production or storage to their point of sale are generally known as distributors, while those that specialize in the delivery of goods to the consumer are known as delivery services. Postal, courier, and relocation services also deliver goods for commercial and private interests. Consumer goods delivery Most consumer goods are delivered from a point of production (such as a factory or farm) through one or more points of storage (warehouses) to a point of sale (such as retail stores or online vendors), where the consumer buys the good and is responsible for its transportation to point of consumption. There are many variations on this model for specific types of goods and modes of sale. Products sold via catalogue or the Internet may be delivered directly from the manufacturer or warehouse to the consumer's home, or to an automated delivery booth. Small manufacturers may deliver their products directly to retail stores without warehousing. Some manufacturers maintain factory outlets which serve as both points of storage and points of sale, selling products directly to consumers at wholesale prices, although many retail stores falsely advertise as factory outlets. Building, construction, landscaping and like materials are generally delivered to the consumer by a contractor as part of another service. Some highly perishable or hazardous goods, such as radioisotopes used in medical imaging, are delivered directly from manufacturer to consumer. Home delivery is often available for fast food and other convenience products, e.g. pizza delivery. Sometimes home delivery of supermarket goods is possible. A milk float is a small battery electric vehicle (BEV), specifically