Protoplanetary disks are the birthplaces of planets but the spatial resolution at long wavelengths has so far been insufficient to resolve the critical 5-30 AU region. The Atacama Large Millimeter Array (ALMA) now allows us to zoom in to nearby disks and determine the physical and chemical structure associated with planet formation. This talk will provide examples of recent work on observations and models of protoplanetary disks in various stages of evolution. Surveys of large numbers of disks provide insight into typical masses and sizes, revealing surprisingly weak gas emission.
Special attention will be given to transitional disks, which are a subset of disks with evidence for sharp-rimmed cavities (gaps or holes). They are the best candidate sources for harboring just-formed
giant planets. ALMA allows imaging of both the gas and dust in these disks, providing constraints on the properties of any young planets. Some prospects for JWST will be mentioned.