Time-delays and data sampling are unavoidable in modern control systems that employ digital technology and in networked control systems, where the plant is controlled via communication network. Time-delay is usually a source of instability, but for some systems, the presence of delay can have a stabilizing effect. My research topics include constructive robust control methods in the presence of delays and data sampling as well as extensions of a recent time-delay approach to averaging with application to extremum seeking (on-line learning) and vibrational control