A plastid is a type of organelle found in the cells of plants and some algae. These structures are essential for various functions, including photosynthesis, storage of starches, and the synthesis of pigments. The most well-known plastid is the chloroplast, which contains chlorophyll and enables plants to convert sunlight into energy. Plastids can change their form and function depending on the needs of the cell. For example, chromoplasts are responsible for the bright colors in fruits and flowers, while amyloplasts store starch. Together, these organelles play a crucial role in the growth and development of plant life.