A 7-dimensional Riemannian manifold (M,g) is called a G2 manifold if the holonomy group of its Levi-Civita connection of g lies inside G2. In this talk, I will first give brief introductions to G2 manifolds, and then discuss relations between G2 and contact structures. If time permits, I will also show that techniques from symplectic geometry can be adapted to the G2 setting. These are joint projects with Hyunjoo Cho, Firat Arikan and Albert Todd.