Protecting groups are used in synthetic chemistry to ensure a reaction occurs in a controlled manner and in as good a yield as possible. They may also be used to change the reactivity of a molecule to allow alternative chemistry to take place. This course summarises the functionalities most in need of protecting, commonly used reagents and methods to allow these transformations plus conditions to remove the groups when desired. A multistep synthesis of an approved drug is highlighted to show the usefulness of orthogonal protecting groups