Organic and inorganic compounds are members of large class of chemical compounds.
We talk about organic compounds when we talk about living organisms. There is an international union of pure and applied chemistry which normally gives definitions to various chemical terms. But there are not any clear cut definitions for organic and inorganic substances and it still remains an open debate from different perspectives of chemists and biologists.
Organic compounds are said to be the ones that contain a carbon-hydrogen bond. Most of the inorganic compounds do not contain carbon. There are many exceptions to this definition in the case of both organic and inorganic compounds. Organic substances include nucleic acids, fats, sugars, proteins, enzymes and fuels. All these substances include a carbon-hydrogen bond.
Inorganic substances include water, metals, non metals, acids, bases, salts and gases like carbon dioxide, oxygen, minerals like oxides and sulfides. Diamond is made of carbon and yet is an inorganic substance. Though oxygen and carbon dioxide are associated with living organisms, they are inorganic too.
There are organic compounds that do not have any carbon hydrogen bonds like urea (CO(NH2)2) which is the main constituent of urine and carbon tetrachloride (CCl4). CCl4 is considered organic due to its chemical behavior. Methane (CH4) is an organic compound. The series CH4, CH3Cl, CH2Cl2 and CHCl3 are all organic and CCl4 being the final member of the series that behaves in the same way as other compounds in this group. The organic molecules normally have poor water solubility, poor electrical conductivity and they also possess low melting points.