Widefield microscopy refers to a basic sample illumination principle in microscopy. Since widefield microscopy permanently illuminates the whole sample, it can be distinguished from confocal microscopy where only one single focal spot is illuminated and recorded at a time. Typically, widefield microscopy utilizes light sources such as halogen, metal halide lamps or LED for sample illumination. Detection is performed through oculars or with the help of a digital camera. Several contrast methods increase widefield microscopy capabilities, starting from Phase Contrast through to Differential Interference Contrast (DIC) or fluorescence, to name but a few. Computer based deconvolution can be applied to increase widefield fluorescence image quality and enable 3D image reconstruction. Moreover, TIRF and GSDIM super-resolution microscopy can be assigned to widefield microscopy.