The service sector or tertiary sector is the economic sector that encompasses activities related to services that do not produce or transform material goods. They generate "Service (economy)" services that are offered to satisfy the needs of any population in the world.

It includes subsectors such as commerce, communications, call center, finance, tourism, hospitality, leisure, culture, entertainment, public administration and the so-called public services, provided by the State or private initiative (health, education, long-term care, among others).

Directs, organizes and facilitates the productive activity of the other sectors (primary sector and secondary sector). Although it is considered a sector of production "Production (economy)"), its main role is actually found in the next two steps of economic activity: distribution "Distribution (business)") and consumption.

The predominance of the tertiary sector over the other two in the most developed economies allows us to speak of the tertiarization process. The Nobel Prize in economics, Paul Krugman, argues that the lower productivity of the service sector and the difficulty in improving its productivity is the main factor in the stagnation of living standards in many countries.[1]​.

The service sector is made up of areas of the economy such as:.

Utilities are often considered part of the tertiary sector when they provide services to people, although when the infrastructure of the utility is created it is often considered part of the secondary sector, although the same business may be involved in both aspects of the operation. Economies tend to follow a progression of development that takes them from a heavy reliance on agriculture towards the development of industry (e.g. automobiles, textiles, shipbuilding, steel, mining) and finally towards a service-based structure. While the first economy to follow this trajectory in the modern world was the United Kingdom, the speed at which other economies have later made the service-based transition, sometimes called post-industrial, has accelerated above this.

The term service economy, in contrast, refers to a model where all possible economic activity is treated as a service. For example, IBM treats its business as a service business. Although it still makes high-performance computers for specific applications, it considers physical goods a small part of the "business solutions" sector.