After primary and secondary sectors, there is a third sector called the service sector also known as tertiary sector. Activities that fall under the service sector help in the development of the primary and secondary sectors by not directly producing a good but helping these sectors by activities that are an aid or a support for the production process.
For example, goods that are produced in the primary or secondary sector would need to be transported by trucks or trains and then sold in wholesale and retail shops. At times, it may be necessary to store these goods in godowns. We may also need to talk to others over telephone or send letters (communication) or borrow money from banks (banking) to help production and trade. Transport, storage, communication, banking and trade are some examples of service or tertiary sector.
Since these activities generate services rather than goods, they promote primary and secondary sectors by providing expertise, finance, transportation, advertisement, etc.
