This lecture discusses use of microwaves for remote sensing, what is radar and its applications. It is shown which properties of microwaves make them very valuable for remote sensing and how information of a remote object can be recovered by means of microwaves. Radar is presented as an instrument needed to extract above mentioned information from microwaves and multi-disciplinary nature of the radar is demonstrated. Brief history of radar developments in Delft is presented. Directions of future research are outlined. Contributions of the radar research to the Delft Research Initiatives are presented.