Introduction:
(i) Sustainable development is concerned with the welfare of the present and future generation.
(ii) It aims at satisfying the luxury wants of the rich and the basic necessities of the poor.
Definition:
(i) Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs.
Goals:
(i) It is crucial to harmonize three core elements such as economic growth, social inclusion and environmental protection.
(ii) A set of 17 goals for the world's future can be achieved before 2030 with three unanimous principles fixed by United Nations such as Universality, Integration and Transformation.
1) End poverty in all its forms everywhere.
2) End hunger, achieve food security and improved nutrition and promote sustainable agriculture.
3) Ensure healthy lives and promote wellbeing for all at all ages.
4) Ensure inclusive and quality education for all and promote lifelong learning.
5) Achieve gender equality and empower women and girls.
6) Ensure access to water and sanitation for all.
7) Ensure access to affordable, reliable, sustainable and modern energy for all.
8) Promote inclusive and sustainable economic growth, employment and decent work for all.
9) Build resilient infrastructure, promote, sustainable industrialization and foster innovation.
10) Reduce inequality within and among countries.
11) Make cities inclusive, safe, resilient and sustainable.
12) Ensure sustainable consumption and production pattern.
13) Take urgent action to combat climate change and its impacts
14) Conserve and sustainably use the oceans, seas and marine resources.
15) Sustainably manage forests, combat desertification, stop and reverse land degradation, stop biodiversity loss.
16) Promote just, peaceful and inclusive societies.
17) Revitalize the global partnership for sustainable development.

Introduction:
1. Externality refers to external effects or spillover effects resulting from production or consumption on the third parties.
Definition:
1. It may be defined as "the cost or benefit imposed by the consumption and production activities of the individuals on the rest of the society not directly involved in these activity and towards which no payment is made".
Types:
1. Beneficial externalities are called "positive externalities".
2. Adverse externalities are called "negative externalities".
Positive Consumption Externality
1. When some residents of a locality hire a private security agency to patrol their area, the other residents of the area also benefit from better security without bearing cost.
Negative Consumption Externality
1. A person smoking cigarette gets satisfaction but this act causes dissatisfaction to the non-smokers who are driven to passive smoking.
Positive Production Externality
1. The ideal location for beehives is orchards.
2. While bees make honey, they also help in the pollination of apple blossoms.
3. The benefits. accrue to both producers (honey and apple).
4. This is called reciprocal untraded interdependency.
Negative Production Externality
1. They include pollution generated by a factory that imposes costs on others.
2. The emissions and effluents of a factory cause air and water pollution.
3. Water becomes contaminated and unfit for drinking (e.g.) Tanneries.
4. The innocent community bears the external cost for which it is not compensated.

(i) Strong economic growth or high GDP growth leads to excessive use of resources.
(ii) Natural resources are essential inputs for production in many sectors;
(iii) Production and consumption lead to pollution and other pressures on the environments.
(iv) Poor environmental quality affects economic growth and well being by lowering the quantity and quality of resources or due to health impact.
(v) There is the need to balance growth and the sustainability of eco system.
(vi) So we have to ensure our sustainable existence, consume less and curb economic growth.