In this paper we shortly review theoretical progress in the field of active matter, focusing on the continuum theory of dry systems, in which momentum of active particles is not conserved due to the interaction between the particles and a substrate or medium. In particular, we review the phenomenological way of deriving hydrodynamic equations for both polar and apolar systems, and the predictions of these theories such as long-ranged orientational order in two-dimensional polar systems and giant number fluctuations. The comparisons among theoretical predictions, numerical results, and experimental evidence are also summarized.