The retail refers to the sale of goods for consumer (the end-user). This is made in small quantities for big number of individuals.
The retail is helpful for manufacturers who produce the goods but don't need to care about all the other amount of work that is needed for the production to arrive to consumers (labor, rent, advertising, ect.).
Opposite to the retail is wholesale which refers to selling large quantities of goods to small number of retailers. The retail is more expensive than the wholesale.