Vertical merger is a merger in which two businesses in the same supply chain combine together to form one company.
Horizontal merger is a merger of two businesses operating in the same industry. It is a merger of competitors and is also called horizontal integration.
Background integration is a type of vertical integration in which a business falling later in a supply chain integrates with a business falling earlier in a supply chain.
Forward integration is a type of vertical merger (vertical integration) in which a supplier acquires a manufacturer or a manufacturer acquires a distributor.