Pollution is commonly defined as the dirtying of a resource for human needs. Pollution can have its own consequences when it is over level. When humans need more and more work done, the waste products are released as pollutants.  There are some sorts of pollution that are not caused by waste products, but those are not dangerous to the environment as much as pollutants are. There are five main types of pollution: soil, water, air, noise and light.
Soil or land pollution is defined as pollution of the topsoil by dumping large amounts of waste on it. Soil pollution is common in semi-urban areas, where waste management is poor and a huge chunk of homely waste in plastic bags gets dumped on certain places. This causes flies to spread across and thus results in the contagion of several diseases.
Water pollution is the dirtying of water. This is caused by large quantities of dangerous waste being dumped into water sources. This can be curbed by filtering waste before emptying it into a water source or refraining from doing so.
Air pollution is the pollution of fresh air. It is caused by factories releasing huge quantities of smoke and also burning of plastic. This can be curbed by isolating such factories from residences and incinerating plastic than burning it.
Noise pollution is not harmful to the environment like the other three are, but it is harmful to the human body. This is caused by loudspeakers, and dangerously loud music which can result in both temporary and permanent hearing problems and even loss of hearing.
Light pollution is not harmful to the environment, neither is it harmful to the body. This causes some stars to be invisible in the sky as there is too much light.
We must always be alert about pollution and curb it whenever required.