Organism growth refers to the process by which living beings increase in size and mass over time. This growth occurs through cell division and the accumulation of new cells, allowing organisms to develop from a single cell, like a fertilized egg, into complex structures, such as plants or animals. Different organisms grow at varying rates and in distinct ways. For example, trees may grow slowly over many years, while bacteria can double in size within hours. Factors such as nutrition, environment, and genetics play crucial roles in determining the growth patterns of each organism.