Ultrafast ultrasound is an imaging technique intended to replace conventional ultrasound scanning when very high temporal resolutions are needed, e.g. to detect movements or to reduce motion artefacts. Traditionally, echography consists in conveying focused ultrasound waves line by line and in juxtaposing the received backscattered echoes from each line. In the last decade, the development of parallel computing, especially in terms of GPUs (graphics processing units), paved the way to the definition of a new method for ultrasound imaging, namely the plane wave transmission. Thanks to this new technique, it is possible to insonify the entire image area in a single transmission, rather than using a number of focused lines.