Most foods and merchandise did not come in individually wrapped consumer-sized packages, so an assistant measured out and wrapped the precise amount requested by the consumer. This offered opportunities for social interaction: many regarded this style of shopping as "a social occasion" and would often "pause for conversations with the staff or other customers". These practices were by nature slow and had high labor intensity and therefore also quite expensive. The number of customers who could be attended to at one time was limited by the number of staff employed in the store. Shopping for groceries also often involved trips to multiple specialty shops, such as a greengrocer, butcher, bakery, fishmonger and dry goods store, in addition to a general store. Milk and other items of short shelf life were delivered by a milkman. The concept of an inexpensive food market relying on economies of scale was developed by Vincent Astor. He founded the Astor Market in 1915, investing $750,000 of his fortune into a 165′ by 125′ (50×38-metre) corner of 95th and Broadway, Manhattan, creating, in effect, an open-air mini-mall that sold meat, fruit, produce and flowers. The expectation was that customers would come from great distances ("miles around"), but in the end, even attracting people from ten blocks away was difficult, and the market folded in 1917.The concept of a self-service grocery store was developed by entrepreneur Clarence Saunders and his Piggly Wiggly stores, the first of which opened in 1916. Saunders was awarded several patents for the ideas he incorporated into his stores.
Supermarkets are investing in micro-fulfillment centers with the hope that automation can help reduce the costs of online commerce and ecommerce by shortening the distances from store to home and speeding up deliveries. In short, MFCs are said by many to be the key to profitably fulfilling online orders. Types
U.S. categorization
The U.S. FMI food industry association, drawing on research by Willard Bishop, defines the following formats (store types) that sell groceries:

Organic and environmentally-friendly supermarkets
Some supermarkets are focusing on selling more (or even exclusively) organically certified produce. Others are trying to differentiate themselves by selling fewer (or no) products containing palm oil. This as the demand of palm oil is a main driver for the destruction of rainforests. As a response to the growing concern on the heavy use of petroleum-based plastics for food packaging, so-called "zero waste" and "plastic-free" supermarkets and groceries are on the rise. Growth in developing countries
Beginning in the 1990s, the food sector in developing countries has rapidly transformed, particularly in Latin America, South-East Asia, India, China and South Africa. With growth, has come considerable competition and some amount of consolidation. The growth has been driven by increasing affluence and the rise of a middle class; the entry of women into the workforce; with a consequent incentive to seek out easy-to-prepare foods; the growth in the use of refrigerators, making it possible to shop weekly instead of daily; and the growth in car ownership, facilitating journeys to distant stores and purchases of large quantities of goods.