How are specialization and trade related? Basic forms of trade?

The relationship of specialization and exchange made it possible to:
• to combine the desire of people to receive as many different goods and services as possible with the ability of an individual, a firm to produce only a small range of goods;
• to receive faster in the maximum assortment a larger volume of quality goods.
Trading can be organized in various forms.
Economists distinguish between wholesale trade (large lots of goods are sold, usually for subsequent resale) and retail (goods are sold individually or in small quantities for personal, family consumption).