Hox genes are a group of related genes that play a crucial role in the development of an organism's body plan. They help determine the identity and arrangement of body segments during embryonic development. Found in many animals, these genes are highly conserved, meaning they have remained relatively unchanged throughout evolution. These genes are organized in clusters on chromosomes and are expressed in a specific order that corresponds to the body regions they influence. For example, in fruit flies, different Hox genes control the development of segments like the head, thorax, and abdomen, ensuring that each part of the body develops correctly.