T2K is a long-baseline neutrino oscillation experiment sited in Japan that explores neutrino oscillations via ν_µ disappearance measurements and ν_µ → ν_e appearance measurements. Neutrino mixing angles and mass differences have been measured under the assumption of both of the possible mass orderings, and constraints have been set on the CP-violating phase δ_CP. The best-fit results for the mixing angles sin² θ₂₃ for normal mass ordering and for inverted mass ordering, respectively, are 0.532^+0.030_−0.037 and 0.532_−0.035^+0.029, with corresponding mass differences in each case of ∆m²₃₂= (2.452^+0.071_−0.070) ×10⁻³ eV² and ∆m²₁₃= (2.432_−0.071^+0.069) ×10⁻³ eV². The parameter sin² θ₁₃ was measured to be 0.0268^+0.0055_−0.0043 (normal ordering) and 0.0300_−0.0050^+0.0059 (inverted ordering). The 1σ allowed region for δ_CPis [−2.509,−1.260] for normal ordering. No region of inverted ordering is included in the 1σ confidence level. In both cases, the CP-conserving values of δ_CP= 0, π have been excluded at the 2σ level. T2K has seen a small preference for normal ordering over inverted ordering with a Bayes factor of 8.0.