The environment is the sum of total living beings, non-living things, as well as the economic, social and cultural conditions, present in our surroundings. Thus, living beings need the favourable environment for survival. Human beings depend upon other animals, vegetables and physical things found in their surroundings to fulfill their basic needs. Air, water, soil, vegetation, minerals, living organism etc. are found on the earth and human are inseparable from these things.

Four environmental elements in the absences of which the survival of human beings is impossible are defined as follows:

1. Air: Air is the most important element. Human being needs air to service. Fresh air keeps them healthy. Without air, the survival of human being is impossible because oxygen is obtained from the air itself which is most necessary for survival.
2. Water: water is an important environmental element. Human being needs water to drink and without water it is impossible to survive. Pure water is needed for healthy life.
3. Soil: All the living organisms of the earth depend on soil. The food grains, essential for human beings, come from the soil. People depend on it only because of the capacity of production of grains, fruit, flower etc.
4. Vegetation: The planet, trees, grass, fruit, flower, etc .of our dependent upon the termed as vegetation. Human beings are totally dependent upon vegetation for eating and to get oxygen. So, it is essential for survival.

Soil is found on the upper surface of the earth crust. All the living creatures on the earth depend on the soil. All types of food, grains, vegetables, fruits, flowers etc. grow on land or soil. So we are dependent on the soil. In case the required food grains are not produced in the soil, then it will be difficult for man and other living beings to survive on the earth. Besides, the soil has been a good habitat for most plants and animals including man. In the absence of land, we are left to die. Factories, roads, bridges, palaces etc. are all built on land. Land beings so important must be conserved. It's quality and quantity deteriorate, our lives will be highly affected and survival would be far from reach.

Nutritious food makes us active, energetic and physically, mentally fit. Nutritious food helps to development our immune power and body will be safe from various sorts of diseases. Thus, nutritious food is most important thing in our life.

Water is important natural resources. 70% of our body is composed of water. The scarcity of water has a negative effect on animals and human beings. Water is used to drink, clean, irrigate, bath and so on. Human settlement is successful on the bank of water resources. Industrial pollutants, drainage and wastage mixed in water resources pollutes the water.

Medicinal plants are the vital components of pharmacy. Harro, barro, bhojo, sarpagandha, jatamasi (spikenard), panchaunle, yarchagumba are important medicinal herbs. In Nepal, there are about 800 types of medicinal herbs in Nepal but only 70 are used as medicine. Forest degradation is the major cause of degradation in medicinal herbs.