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Soil is a mixture of organic matter with minerals and fluids and organisms that together support life. The body of soil of Earth called the Pedosphere has four important functions. Soil functions as a medium for plant growth. Soil functions as a means of water storage supply and purification. Soil is a modifier of Earth atmosphere. Soil is a habitat for organisms. All of these functions in their turn modify the soil and its properties. Soil is also commonly referred toas earth or dirt. Some scientific definitions distinguish dirt from soil by restricting the former term specifically to displaced soil. The Pedosphere interfaces with the whole biosphere which includes the lithosphere and the hydrosphere as well as the atmosphere. Soil consists of a solid phase of minerals and organic matter as well as a porous phase that holds gases and water. Accordingly soil scientists can envisage soils as a three state system of solids and liquids along with gases. Soil is a product of several factors like the influence of climate relief or organisms and the soil parent materials interacting over time. It continually undergoes development by way of numerous physical and chemical processes. This also includes biological processes which include weathering with associated erosion. Given its complexity and strong internal connectedness soil ecologists regard soil as an ecosystem. In engineering terms soil is included in the broader concept of regolith which also includes other loose material that lies above the bedrock as can be found on the Moon and on the other celestial objects. Soil functions as a major component of the ecosystem of Earth. Ecosystems around the world are impacted in far reaching ways by the processes carried out in the soil with effects ranging from ozone depletion and global warming to rainforest destruction and water pollution. Soil acts as an important carbon reservoir with respect to carbon cycle of Earth and it is potentially very reactive to human disturbance and climate change. As the planet warms it has been predicted that soils will add carbon dioxide to the atmosphere due to increased biological activity at higher temperatures which is a positive feedback. This prediction has however been questioned on consideration of more recent knowledge on carbon turn over in soil. Soil acts as an engineering medium and a habitat for soil organisms. It is a recycling system for nutrients and organic wastes and a regulator of water quality. It is also a modifier of atmospheric composition and a medium for plant growth making it a critically important provider of ecosystem services. Since soil has a tremendous range of available niches and habit at sit contains most of the genetic diversity present on Earth. A gram of soil can contain billions of organisms belonging to thousands of species which are mostly microbial and largely still unexplored. Soils can effectively remove impurities or kill agents of disease and degrade contaminants also. This latter property is called natural attenuation. Typically soils maintain a net absorption of oxygen and methane and undergo a net release of carbon dioxide and nitrous oxide. Soils offer plants physical support along with nutrients and air and water. It also provides temperature moderation and protection from harmful toxins. Soils provide readily available nutrients to plants and animals by converting