This talk will be an introduction to Nakajima quiver varieties, focusing on type A quivers. We will begin with a brief recount of quiver representations, including discussion of kernels and indecomposables. We will define the notion of framing, and impose a ``stability condition" on framed quiver representations to obtain what we will call pre-quiver varieties, of which the Grassmannians and complete flag varieties are examples. Next, we will introduce the doubled framed quiver. Imposing both the stability condition and additional "moment map condition" on doubled framed quiver representations yields the notion of a Nakajima quiver variety. Examples include cotangent bundles of Grassmannians and complete flag varieties.