Uncertainty in future climate prediction is driven by uncertainties in the forcing of the climate system, as well as uncertainties in the feedbacks that determine the response to climate forcing. The biggest uncertainty in forcing is the effect of aerosols on clouds, and the biggest uncertainty in feedbacks are the cloud feedbacks. This presentation will review the state of knowledge of aerosol-cloud interactions and the current state of knowledge about cloud feedbacks. The presentation will focus on what drives the uncertainty and outstanding questions. This will lead to a discussion of some new work on understanding the critical role of cloud microphysics in both climate forcing and climate sensitivity. Cloud microphysics is critical to understanding radiative forcing, and there are important subtleties that arise when calculating cloud feedbacks.