Current views on low-mass star formation
  The process that leads to the formation and early evolution of low-mass stars is in a broad sense well understood theoretically and carefully traced observationally. The largest uncertainties in this framework reside in the poorly known initial conditions for the origin and gravitational collapse of dense cores within molecular clouds. In this review, we will discuss the evidence for an accelerated pattern of star formation in clusters and associations, the physical origin of this phenomenon, and the age spread in low-mass star forming regions. On the latter issue, we will show how the observation of lithium depletion in young clusters, such as the Orion Nebula Cluster and the Upper Scorpius association, can provide an independent estimate of their ages and age spreads with important implications on the understanding of the initial conditions and history of star formation. 
Francesco Palla, Sofia Randich