A leaf is a flat, green part of a plant that is primarily responsible for photosynthesis, the process by which plants convert sunlight into energy. Leaves are typically attached to a stem and come in various shapes and sizes. They contain chlorophyll, a pigment that captures sunlight, allowing the plant to produce food and release oxygen into the atmosphere. In addition to photosynthesis, leaves play a role in transpiration, which is the process of water vapor leaving the plant. This helps regulate temperature and maintain moisture levels. Different types of leaves, such as those from deciduous trees or evergreen trees, have unique adaptations to their environments.