Essential genes are those genes that are necessary for the survival of an organism. They are responsible for the formation and maintenance of fundamental biological processes. Some synonyms for the term 'essential gene' include: vital gene, critical gene, indispensable gene, and necessary gene. These terms describe genes that cannot be substituted or removed without causing harm to the organism. Essential genes are present in all living organisms, from bacteria to humans, and they are required for proper functioning of cells and tissues. Understanding the function of essential genes is important for identifying potential drug targets and developing new treatments for diseases caused by genetic mutations or disruptions in gene expression.