Linked from
The 20 pages that link to Taylor's theorem, each with the reason it gives.
Taylor seriesRelated: Its remainder term quantifies the error when a Taylor series is truncated.
Hessian matrixRelated: The Hessian supplies the quadratic term in the local approximation.
Rolle's theoremRelated: Rolle's theorem is used in deriving common forms of the Taylor remainder.
Itô's lemmaRelated: A second-order expansion explains why squared Brownian increments survive.
Brook TaylorRelated: Taylor’s 1715 treatise gave an early general statement of this result.