SO Webloquio: Optical interferometric studies of star and planet formation

A first step towards understanding planetary formation is the characterisation of the structure and evolution of protoplanetary discs.  Although the large scale disc is understood in some detail, very little is known about the inner few au. In this region, dust grains sublimate, and accretion and ejection take place, affecting the entire disk structure and evolution. In this talk, I will review how optical interferometric observations can help us to probe the innermost regions of protoplanetary disk. In particular, I will focus on the main characteristics of this inner region as probed through VLTI-GRAVITY observations of dust and gas tracers. Finally, I will show what is our progress on image reconstruction of the inner disk.