Gross margin is the revenue left over after the direct costs of delivering the product, hosting, customer support, payment processing, third-party services. It's the most fundamental unit-economics measure: low gross margin caps how much the company can spend on sales, marketing, R&D, and operations.
SaaS gross margin typically runs 70 to 85%; transactional businesses 30 to 60%; e-commerce and marketplaces vary widely depending on take rate. The trend matters as much as the level, gross margin should expand as the company scales.