Green Fluorescent Protein (GFP) is a protein that exhibits bright green fluorescence when exposed to ultraviolet or blue light. Originally discovered in the jellyfish Aequorea victoria, GFP has become a vital tool in molecular and cellular biology. Its ability to glow allows scientists to visualize and track proteins, cells, and other biological processes in real-time. GFP can be genetically engineered to attach to other proteins, making it easier to study their behavior and interactions within living organisms. This versatility has led to its widespread use in research, including studies on gene expression, cell development, and neuroscience.