What it means
TAM (Total Addressable Market): everyone who could ever use a solution like yours. SAM (Serviceable Addressable Market): the portion your model, geography, and product can actually serve. SOM (Serviceable Obtainable Market): the share you can win in the near term given competition and resources.
Why it matters
Investors and boards use it to judge ambition and realism; operators use it to set targets that are neither delusional nor timid. For GCC plays, the gap between TAM and SAM is often large — a global TAM, but a SAM shaped by language, regulation, and payment infrastructure.