Immediate Early Genes (IEGs) are a group of genes that are rapidly activated in response to various stimuli, such as growth factors, stress, or neuronal activity. They play a crucial role in cellular processes, including differentiation, survival, and synaptic plasticity. IEGs are often the first genes expressed after a stimulus, making them important for understanding how cells respond to changes in their environment. Common examples of IEGs include c-Fos, c-Jun, and Arc. These genes help regulate the expression of other genes and are involved in processes like memory formation and learning. Studying IEGs can provide insights into various biological functions and diseases, including neurodegenerative disorders and cancer.