All the materials we use can be broadly classified into two groups :
(a) Natural Resources, (b) Man-made Resources.
(a) Natural resources are those resources which are present in our nature, gifted by God. They can be freely used. Soil, air, sunlight, water, wildlife, etc. are some natural resources.
(b) Man-made resources are those resources which are formed by various efforts of man and are artificial. Plastics, fibres, electricity, etc. are all artificial resources.
On availability of materials natural materials can further be classified as :
(i) Inexhaustible Natural Resources : Those resources which are present in unlimited quantity and will never get exhausted by human activities. Sunlight, air, soil, etc. are some inexhaustible natural resources.
(ii) Exhaustible Natural Resources :
Those resources which are available in limited amount and will get finished by human activities. Petroleum, coal, wildlife, forests, etc. are some examples of exhaustible natural resources.