Business: what is vertical integration?

Self-tutoring about business terms: the tutor mentions vertical integration.

Vertical integration is a type of business organization in which numerous different activities are carried out by the same company because they are related. The company may consume most of the activities internally in order to produce only one product that they sell. A logging company that builds its own roads, falls trees, hauls the logs, then also owns the mills where the logs are made into lumber is an example of vertical integration.

Source:

Belshaw, John Douglas. Canadian History – Pre-Confederation, 2nd edition. Victoria, BC: BCampus, 2020, https://opentextbc.ca/preconfederation2e/