A micro-channel plate is an array of miniature electron multipliers with pore size in the range 6-25 microns and length-to-diameter ratio between 40 and 100. Each channel is acting as a compact, continuous dynode chain for signal amplification resulting in a typical gain of 10^3 per single plate, and up to 10^7 for plates used in cascade arrangement. Micro-channel plates feature high spatial resolution (limited by the channel size and pitch) and ultra-high time resolution down to 10 ps. In addition, they are radiation hard and very robust to magnetic fields. They have been originally developed and integrated as an amplification element in image intensifiers for night vision applications. These devices have single-photon sensitivity and very low noise (essentially dominated by the photocathode dark count rate). In high-energy physics, they have been used as such for scintillating fibre tracker readout. Given their very short transit time spread, micro-channel plate photomultiplier tubes are also being used for time-of-flight and particle identification applications. For this purpose, dedicated anode segmentation and readout electronics are required, and the tubes must survive a number of years in a high occupancy environment. Driven by these applications, various new manufacturing processes (such as atomic layer deposition) have been developed over the last few years, resulting in a significant improvement in terms of efficiency, noise, and lifetime performance.