Introduction to microscopy. From the magnifying lens to the compound microscope. Application fields of optical microscopy in biology. Fundamentals of optics. Formal concepts and descriptions of: magnification, resolution and contrast. Optical microscopy in transmitted and reflected light, fluorescence microscopy. Comprehensive explanation of the most used protocols for the preparation of biological samples for their study under an optical microscope. Laser confocal, spinning disc, TIRF, multi-photon, light sheet fluorescence microscopy and mentions of advanced techniques for super-resolution microscopy and electron microscopy.