Brillouin microscopy is an emerging optical imaging and spectroscopy technique which allows to probe mechanical properties of living cells using light. Mechanical forces have recently become important in cell, tissue and developmental biology as they are thought to regulate a number of different properties and behaviours. Brillouin microscopy offers the ability to measure these mechanical properties in a non-invasive way with high spatial and temporal resolution in living cells, and also gives access to internal structures, it is not restricted to surface measurements, like many other techniques ( atomic force microscopy). By a mix of lectures and hands-on classes this course aims at bringing this emerging technique closer to the life scientists.