The oxidation state, also known as oxidation number, is a concept in chemistry that indicates the degree of oxidation of an atom in a compound. It reflects the number of electrons an atom gains, loses, or shares when forming chemical bonds. Oxidation states are usually represented as integers, which can be positive, negative, or zero, and help in understanding the electron transfer in redox reactions. In a molecule, the oxidation state can be determined by following specific rules, such as assigning a state of -2 to oxygen and +1 to hydrogen in most compounds. These rules help chemists predict how atoms will interact in chemical reactions, making oxidation states essential for balancing chemical equations and understanding reaction mechanisms.