Paddy (rice) is grown in more than a hundred countries, with a total harvested area of approximately 158 million hectares, producing more than 700 million tons annually (470 million tons of milled rice). Nearly 640 million tons of rice are grown in Asia, representing 90% of global production. Several factors are responsible for reducing the paddy productivity in worldwide. However, weed infestation is the major biotic threat to productivity of transplanted paddy. Weeds are competed with paddy by their high adaptability and faster growth, dominate the crop habitat and reduce the yield potential of paddy. Weed management is an important agro-technique for successful transplanted paddy cultivation. It can be achieved, either manual or mechanical or chemical weed control methods. Even though, hand weeding is an effective method of weed management, scarcity of labour and cost of weeding force the farmers to depend on chemical weed management. Herbicides offer the most effective, economical and practical way of weed management.