Linked from
The 31 pages that link to Inner product, each with the reason it gives.
Born ruleRelated: Measurement amplitudes are inner products between states and outcome vectors.
OrthogonalityRelated: A pair is orthogonal precisely when this function evaluates to zero.
Orthogonal matrixRelated: Preserving inner products is equivalent to preserving lengths and angles.
Euclidean vectorRelated: It defines the lengths and angles that make a vector space Euclidean.
Bra–ket notationRelated: The expression ⟨φ|ψ⟩ represents an inner product.