All companies make use of IT these days.

An IT company may be as simple as company established for developing websites, web applications, desktop applications, mobile applications (Android/iOS) to the company that works on Big Data, AI, Machine Learning , etc. (Big Data may be of different fields such as Bank,Health, Education, Industry and Governmental Organizations.)

Some companies may work on outsourcing projects.

B2B, B2C are the business models used by a company .

IT companies are not the companies that sale products or services, they are the actual business company. But the IT companies makes software , (internet) platform (eg. B2B web app or mobile app) , analysis of data of those actual companies.

Mainly There are 7 different types of IT services companies:

  1. Programmers company
  2. Web Development company
  3. Technical Support company
  4. Computer Systems Analyst company
  5. Networking Company
  6. IT Security company
  7. Internet marketing company


Source : quora