Life on Earth depends on solar energy captured by plants - they are the base of most food webs and underpin the functioning of all major ecosystems. Plants release the oxygen we breath. They convert solar energy into chemical energy, providing us with food, fibres, renewable energy sources, and raw materials for many industries. Plants do not carry out these processes in isolation. They interact with other organisms and the physical and chemical environment, communicate and actively adjust to their circumstances. How do they do these things and how can we profit from understanding them?