Industry

• Industrial systems = Inputs → Processes → Outputs, and outputs include finished products, by-products, part-products, and waste.
• Manufacturing is either heavy (big, bulky, huge-scale — e.g. iron & steel) or light (small, precise — e.g. phone assembly).
• The four sectors of the economy — primary, secondary, tertiary, quaternary — are interlinked; one product (like cotton clothing) passes through several of them.
• High-tech industry is the fastest-growing industry type worldwide, relies on constant R&D, and clusters in science parks.
• Where a factory locates depends on a mix of physical factors (raw materials, site, climate, water, energy, routeways) and human/economic factors (capital, markets, government, transport, communications, labour, quality of life).
• No single factor decides location — it's always the least-cost, highest-profit combination (the "optimum location").
• Industry and its location change over time — raw materials run out, costs rise, technology and outsourcing shift where work happens.
• Countries can be classified as pre-industrial (mostly primary sector, e.g. Bolivia, Mozambique), industrial (mostly secondary, e.g. China, India), or post-industrial (mostly tertiary/quaternary, e.g. UK, USA).
• Case study: Pakistan's Iron & Steel Industry at Pipri — a textbook example of how inputs, processes, outputs and impacts all link to a real location.

The Basic Model

Think of any factory as a black box. Stuff goes in one side, something happens inside, and different stuff comes out the other side. Geographers break this into three stages:

• Inputs — the basic ingredients needed just to start the process: raw materials, labour, energy, capital (money), land, buildings, water, even internet access.
• Processes — the actual work done to transform those inputs: cutting, sewing, welding, brewing, painting, moulding, etc. This is the "magic" step where raw stuff becomes a product.
• Outputs — everything that comes out the other end. Note this is not just the finished product — outputs include four different things (see below).

Heavy vs Light Industry

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