Irrigation is the process of supplying water to crop plants through artificial methods like canals, wells, reservoirs, and tube wells. It is important for crop growth and development as water contains oxygen and hydrogen essential for plant growth. Irrigation increases soil moisture for seed germination, root and aerial growth, and nutrient absorption, providing more reliable water than rainfall. Traditional irrigation methods include wells, canals, river lift systems, and tanks, while modern methods like drip and sprinkler irrigation save water but require pumping systems. Over-irrigation can cause problems like mosquito breeding, water logging, and pesticide runoff harming water bodies.