Frequency diverse array (FDA) radar has been studied for more than 15 years and has attracted a lot of attention due to its potential advantages over the well-known phased array radar. The representative feature of FDA is range-angle-time-dependent transmit beampattern and its un-derlying properties are continuously revealed in the research. The formulation and exploitation of the transmit diversity with a frequency increment is the fundamental principle, which brings extra degrees-of-freedom (DOFs) in the transmit dimension. As the FDA radar carries additional inform-ation in range, it provides more flexibility in signal processing and also brings in new technical is-sues. This article overviews the state-of-the-art in FDA radar area and its applications, mainly based on the progress in our group. There are two main catalogs in FDA radar area, namely coher-ent FDA and FDA-MIMO(multiple-input multiple-output) radars. Potential applications including target parameter estimation, ambiguous clutter suppression, and deceptive jammer suppression are discussed.