We will discuss the general notion of symplectic duality (also known as 3D mirror symmetry) between symplectic resolutions of singularities. We will give examples of dual varieties such as Higgs and Coulomb branches, Slodowy varieties and closures of nilpotent orbits. We will then formulate the Hikita-Nakajima conjecture describing (equivariant) cohomology ring of a symplectic resolution in terms of the dual variety. This conjecture should be considered as a generalisation of a classical result by de Concini and Procesi describing the cohomology ring of type A Springer fibers. We will discuss the approach towards the proof of Hikita-Nakajima conjecture and illustrate it in various examples. Time permitting, we will touch on applications of this conjecture. This talk is based on the joint works with Pavel Shlykov (arXiv:2202.09934) and with Do Kien Hoang and Dmytro Matvieievskyi (arXiv:2410.20512).