Homeobox genes are a group of genes that contain a specific DNA sequence known as the homeobox. This sequence is responsible for encoding proteins that regulate the development of structures in animals, including the body plan, major organs, and appendages. Homeobox genes are also referred to as Hox genes, and there are a number of synonyms for this term, including homeotic genes, selector genes, morphogenetic genes, and axial patterning genes. These genes play a crucial role in determining the identity of cells during development and are conserved across a wide range of species, from fruit flies to humans. Understanding the function of homeobox genes is therefore essential to understanding the processes of morphogenesis and cellular differentiation.