Enzyme activity refers to the rate at which an enzyme catalyzes a chemical reaction. Enzymes are biological molecules, typically proteins, that speed up reactions by lowering the activation energy required. Factors such as temperature, pH, and substrate concentration can influence enzyme activity, making it essential for various biological processes. When an enzyme binds to its specific substrate, it forms an enzyme-substrate complex. This interaction facilitates the conversion of substrates into products. The efficiency of enzyme activity is crucial in processes like digestion and metabolism, where enzymes like amylase and lipase play significant roles in breaking down food.