Using the wrong yardstick makes a great business look bad and a terrible one look cheap. Each sector below starts from zero: how the business actually makes money, explained with examples, and only then the handful of numbers that decide its story.
PE compares price to profit. But a bank runs on borrowed money by design, holding ₹10 or more of deposits for every ₹1 of its own. That makes profit look big and hides the real risk, which is not profit but whether the loans get repaid. A bank dies from bad loans, not from a low PE. So you read its loan quality, not its PE.
Gross margin suits businesses where the product varies. Cement is the same grey powder whoever makes it, and it is too heavy to ship far, so it is really a local commodity. What decides profit is cost and distance, captured in one number: profit per tonne of cement. Gross margin tells you almost nothing here.
A sector page explains how an entire industry works before you look at any single company in it: how the businesses make money, what customers actually buy, what drives demand and margins, and the one or two numbers that decide the story. The right yardstick changes from sector to sector, which is why the same metric can flatter a bank and damn a cement maker. Start with the sector, then read any company in it on its own terms.