Porter’s five forces is one the most famous tools in Business world. It talks about:

• How managers can protect firm’s existing rent stream against competition, efficient market operations, or other processes. ( or attack others )
• 3 levels of analysis – i) Short term competitiveness – business rivalry , ii) Rent management against Suppliers and Customers ( Microeconomics ) iii) Slower scanning for new firms or technology ( substitutes ) ( Macroeconomics )
• Categories such as Regulation, labour unions, legislation not included.