in this talk i will survey current results on the long-time existence and behavior of ricci flows in dimensions 2, 3 and higher. moreover, i will point out analogies with construction techniques for einstein metrics. in dimension 3, the ricci flow together with a certain surgery process has been used by perelman, amongst many others, to establish the poincaré and geometrization conjectures. despite the depth of this result, a precise description of the long-time behavior of this flow has remained unknown. for example, it was only conjectured by perelman that it suffices to carry out a finite number of surgeries and that the geometric decomposition of the manifold is exhibited by the flow as $t \to \infty$. recently i was able to confirm perelman's first conjecture and i partially answered his second one. i will first give a brief overview of ricci flows with surgery and explain the finite surgery theorem. next, i will present long-time existence results in dimensions 4 and higher and describe possible further directions in this field.