These documents are intended for students of the common core of biological and agronomic sciences. It introduces them to the various scientific methods and techniques for studying living organisms. The methods for approaching and studying living organisms are quite varied and depend on the object of study: microscopy (photonic and electronic), electrophoresis, chromatography, PCR, spétrophotometry, immuno-enzymatic methods, cell cultures, herbarium, immunocytological methods....etc.