Floer type (co)homology theories are among the most prominent tools in symplectic geometry. They made great advances within the subject possible, but also in other areas of mathematics, such as Algebraic Geometry and Low-dimensional topology. In this talk I will give an exposition of the main ideas underlying the construction of Floer (co)homology theories, and give examples of applications. This is an introductory talk, so no prior knowledge of Floer type theory will be assumed.