The detection of a chemical or biochemical species as well as the evaluation of its quantity or concentration can be done either using analytical instruments such as microscopes or various spectrometers, or using sensors. It is therefore necessary to make as clear a distinction as possible between these two means of analysis knowing that it will inevitably be a little caricatured. The objective of this book is to provide the basics of laboratory techniques based on some simple knowledge. Understanding how these techniques work is necessary for their proper use and for a correct interpretation of the data obtained. This course does not claim to be exhaustive, it is just a very simplified and limited introduction to laboratory techniques. We will begin by addressing some generalities on light itself since the optical and electron microscope is only used to use its properties.