Total Addressable Market (TAM) is the entire universe of demand for a category — the full revenue or volume available if every potential buyer chose your kind of offering, with no constraints on reach or competition. It is the widest of the three figures in the TAM/SAM/SOM hierarchy, and on its own it says only how big the space could be, not how much of it you can realistically serve or capture.
TAM is the top of the TAM-to-SAM-to-Share-of-Market funnel that BRI uses for defensible market sizing in the Financial Logic dimension of the Strategy Framework. A credible TAM is built bottom-up from real segments rather than asserted top-down, then narrowed by reach (to SAM) and by the share you actually capture (to Share of Market). For the full treatment, see the Market Sizing pillar at /supporting/market-sizing. Related Terminology Index entries: Serviceable Addressable Market; Share of Market; Market Sizing; Viability.
