Book excerpt: Green technology is the application of the environmental science and technology for the development and application of products, equipment and systems to conserve the natural resources and environmental management, as well as to minimize or mitigate the harmful effects on the environment by the mankind. Whereas ‘green technology’ is a fascinating term, it expresses the meaning effectively as ‘clean technology’ or in the classical approach ‘environmental technology’. The field of green technology emphasizes constantly evolving areas of environment friendly methods, protocols, principles, techniques, materials, equipment, software & hardware, intelligence & learning, rules & regulations, from technologies for developing non-conventional energy sources such as biofuels to ecofriendly solar power management as greener tools that help in auditing greenhouse gas emissions. Green and clean technology must be sustainable, that is, balancing the fulfilment of human needs without greed, with the protection and conservation of the natural environment and all the resources so that these needs can be met for the present and the future.