Spectroscopy is the study of how light interacts with matter. Spectroscopy is used to determine the structure and functional groups of organic compounds. The course exhibits the key parts of Infrared spectroscopy technique. It is basically intended for beginners with basic knowledges in analytical chemistry. The course starts with a concise introduction and represents the fundamentals of this technique based on the classical Harmonic oscillator model. The students will understand why it is called Vibrational Spectroscopy.A step-by-step explanation is given in order to develop the ability to analyze any IR spectra. The last session of the course contains different examples in order to practice the interpretation of ir spectra. The course focuses on:1) - Basic principles of spectroscopy: absorption of light and vibrations of bonds.2) - How the vibration frequency of a chemical bond can be compared to that of the oscillation of a spring.3) - How to predict by calculation the wavenumber corresponding to any type of chemical bond.4) - Interpretation of IR spectra of hydrocarbons containing single, double and triple carbon-carbon bonds.5) - Influence of hydrogen bonds on the width of the absorption bands of an IR spectrum.6) - Identification of a chemical compound corresponding to a given IR spectrum.