The present needs of resources are met and the conserving of resources for the future are balanced, we call it sustainable development.

Tertiary activities are basically concerned with the distribution of primary and secondary products through a system of transport and trade. (e.g) Banking, Trade and Communications.

Individual resources are resources privately owned by individuals. (e.g.) Apartments.

Human resources are groups of individuals who use nature to create more resources.

Resources once consumed can be renewed with the passage of time are called renewable resources. (e.g) Air, Water, Sunlight.

ON THE BASIS OF DISTRIBUTION:
On the basis of distribution, resources can be classified into localized resources and universal resources.
(i) When resources are present in specific regions they are called localized resources.
(e.g.) Minerals.
(ii) Some resources are present everywhere Such resources are called universal resources.
(e.g.) Sunlight and air.
(ii) On National resources are resources within the political boundaries and oceanic area of a country.
(e.g.) Tropical forest regions of India.

Resource is anything that fulfills human needs.
(i) When anything is of some use it becomes valuable.
(ii) All resources have value.
(iii) The value can be either commercial or non-commercial. Commercial resources have great economic value. (e.g.) Petroleum.
(iv) The Non-commercial resources are very abundant in availability (e.g.) Air.

Classification of Natural Resources:
Natural resources can be classified into different groups depending on origin, development, renewability, distribution, ownership etc
ON THE BASIS OF ORIGIN:
On the basis of origin, resources can be classified into biotic and abiotic resources.
(i) All living resources are biotic resources, plants, animals and other micro organisms are biotic resources.
(ii) Abiotic resources are non-living things. Land, water, air and minerals are abiotic resources.
ON THE BASIS OF DEVELOPMENT:
Based on the level of development, resources can be divided into actual and potential resources.
(i) Actual resources are resources that are being used and the quantity available is ' known. (e.g.) Coal at Neyveli.
(ii) Potential resources are resources that are not being used in the present and its quantity and location are not known. The technology to extract such resources is also yet to be developed. (e.g.) Marine yeast found in the Bay of Bengal and Arabian Sea.
ON THE BASIS OF EXllAUSTFFILLITY:
On the basis of renewability resources can be classified as renewable resources and nonrenewable resources.
(i) Resources once consumed can be renewed with the passage of time are called renewable resources. (e.g.) Air, Water, Sunlight. Misuse of such resources can also limit its available quantity. So, they have to be used wisely.
(ii) Natural resources which are limited can be called non-renewable resources. They become exhausted after use and the time they take to replace does not match the life cycle. (e.g.) Coal, petroleum, natural gas and other minerals.

Mahatma Gandhi blamed "human beings" for depletion of resources because of
(i) Over exploitation of resources
(ii) Unlimited needs of human beings. So, conservation is very important