Pollution is when some harmful substances are added in the environment which alter its natural composition . Polluted water or garbage in the water bodies is a type of pollution. It adds germs and viruses. There are five kinds of pollution: water pollution, air pollution, noise pollution, soil pollution and thermal pollution.But two more also added that are nuclear and visual pollution.
As pollution grows, ways to combat it have grown. Solar energy and wind energy give people clean ways to power their homes. When people use these alternative forms of energy, they put less carbon dioxide into the environment. 
Air can be polluted by many things. Examples include poisonous gases, sulphur dioxide, nitrogen dioxide, carbon monoxide and very small particulates. Smoke and harmful gases released by fires, industries, and thermal power plants cause air pollution. Using coal and wood as fuels for fire cause a lot of air pollution. Petroleum produces less pollution per ton, but it causes a lot of pollution since a lot of it is burned globally. Air pollution may cause health problems such as asthma or other breathing problems.
Water pollution is the presence of harmful materials in water, such as sewage, dissolved metal, waste from farms, factories and crude oil spilled from oil tankers. The three main substances that pollute water are nitrates from fertilizers, sewage and detergents.
Activities such as bathing and washing clothes near lakes, ponds or rivers add nutrients like nitrate and phosphate into the water bodies.This leads to excessive growth of algae on the surface of water. It blocks the penetration of sunlight and air, thus reducing oxygen.
Noise pollution also known as sound pollution is harmful to the brain and hearing of all animals and humans. This includes the sound of vehicles, loud speakers, airplanes, jets, train horns etc. Noise pollution can cause ear problems or even permanent deafness, especially to older people. The schools which are beside the roads suffer from noise pollution. Students cannot concentrate in their studies. Peoples admitted in hospitals which is near to the main roads also suffer. It also causes brain related problems.
Soil pollution (also known as land pollution) is caused when man-made chemicals, such as hydrocarbons, heavy metals, and solvents get into the soil. These chemicals come from industrial activities and using chemical fertilizers and from improper waste in disposal in leacky landfills. Soil pollution can cause health risks. The chemicals can produce harmful vapors, or they can contaminate water supplies underneath the polluted soil. Under the earth Plastic pollution is the accumulation of plastic products in the environment that adversely affects wildlife, wildlife habitat, or humans. It is caused because plastic takes thousands of years to decompose or mix in the earth. Cancer, including leukemia may be caused by the contact with soils contaminated with chemicals. Nervous system damage may be caused by the presence of lead (Pb) in soil, and affects especially children.
Thermal pollution is the harmful release of heated liquid into a body of water or heat released into the air as a waste product of a business.
A common cause of thermal pollution is the use of water as a coolant by power stations and industrial manufacturers. This puts back warm water, and so raises the temperature and decreases the oxygen content of the water. The heat released into the air will cause the air to be warmer which may result in global warming.