Evolution and dispersal of protoplanetary disks

Multiwavelength studies of evolved protoplanetary disks reveal a general trend of changes in the IR excesses, accretion rates, and silicate features, suggestinggrain growth/settling, photoevaporation, and maybe the formation of planets and planetesimals. Nevertheless, within the average-behaviour picture of disk evolution, we observe strong variations between individuals, that may be related to different initial conditions, different environments, and the presence of companions. I will present what multiwavelength observations can do to reveal what is happening in the disk while it is dispersing, how much time is left to form the planets before the disk disappears, and what the first steps of planet formation may look like.