Gross margin

Revenue minus the direct cost of delivering it, as a percentage of revenue.

Example

$100 of revenue costing $20 in hosting and support is an 80% gross margin.

Gross margin is why software is funded and services usually are not. A 25%-margin business needs four times the revenue for the same gross profit.

COGS (Cost of Goods Sold) — The direct costs of delivering your product — the costs that rise with each additional customer.
Contribution margin — Revenue from a unit minus all the variable costs of producing and selling that unit — a step beyond gross margin because it also includes variable selling costs.
LTV (Lifetime Value) — The total gross profit you expect from one customer over the whole relationship.

Producing your own P&L and cash view — Turning categorised transactions into the two reports you will actually use, and the six numbers you should be able to recite from memory. (14 min)
Business models — Subscription, transaction, marketplace, usage, licence. The model shapes your margin, your sales motion and how much money you need. (12 min)
Pricing — Not what competitors charge. A statement about who you are for — and most early startups price far too low. (15 min)
Localisation, currency and pricing — Translation is the smallest part. Currency, payment methods and local price expectations matter more. (12 min)
Build, buy, or do not do it at all — The most valuable engineering decision is usually not writing the code. Three questions that settle it. (10 min)
Scaling product and infrastructure — What breaks is rarely the code. It is the decisions nobody wrote down, and the costs that grew quietly with usage. (12 min)