Energy in an ecosystem flows in a unidirectional manner, starting from the sun, which provides energy for producers like plants through photosynthesis. Herbivores, or primary consumers, feed on plants, transferring energy to higher trophic levels like secondary and tertiary consumers. Decomposers, such as fungi and bacteria, recycle nutrients from dead organisms back into the soil, completing the cycle. Energy transfer is inefficient, with only about 10% moving to the next trophic level, the rest lost as heat. Understanding energy flow is crucial to studying ecosystem productivity, food web dynamics, and the effects of environmental disturbances.