What are the main 20 departments in a company?

A company does not necessarily have to have 20 important departments. It basically depends on the business type of the organization. Yet, there are a few essential departments in a company in order to get the businesses done such as:

Finance

Marketing

Human Resource

Operations

Depending on the magnitude and type of dealings, companies can even have Research, IT, Network, Procurement, Legal departments to name a few..