What Oxidation Means in Chemistry?

In our daily life we come across processes like rusting of objects made of iron, fading of the color of clothes, burning of the combustible substances such as cooking gas, wool, coal etc. What is happening behind these changes? These process fall in the category of specific type of chemical reactions called oxidation-reduction reactions.

Oxidation is the most important high temperature reaction. Oxidation refers to an increase in oxidation state, which means a loss of electrons. In organic chemistry it is often easier to view oxidation as increasing the number of bonds to oxygen or other heteroatoms. Simply oxidation is a process of addition of oxygen or removal of hydrogen to a substance.

An oxidation reaction between a metal (M) and the oxygen (O_2) can be written as 

M(s) + O_2 (g) \rightarrow MO_2(s).
Some of the examples of oxidation reaction are listed below.

1. Rusting of iron - In rusting, iron does not combine directly with oxygen but involves the oxidation of iron in an electrochemical process.
2. Digestion of food in our body - When foods are broken down inside the body during the course of normal digestion oxidation also takes place, the vital difference is that the food energy is made available for our use.
3. Burning of fuels - The combustion of fuels is an oxidation reaction. The combustion of hydrocarbon fuels is a vital source of energy in our economy. Daily we make use of combustion of fuels. In respiration the combustion of foods provides us with energy.
4. Rancidity - The condition produced by aerial oxidation of fats and oils in foods marked by unpleasant smell and taste is called rancidity.