Pollution can be defined as contamination of the environment that directly or indirectly causes harm. This document discusses different types of pollution including air, water, noise, and land pollution. It provides details on the causes, sources, effects and remedial measures for each type. For air pollution, the main causes are listed as rapid industrialization, urbanization, and deforestation. Water pollution sources include domestic and industrial waste. Noise pollution sources include industrial activities, transportation, and construction. Land pollution results from dumping of wastes and excessive use of fertilizers and pesticides.