Human genes are segments of DNA that contain the instructions for building and maintaining the human body. Each gene plays a specific role in determining traits, such as eye color, height, and susceptibility to certain diseases. Humans have approximately 20,000 to 25,000 genes, which are organized into 23 pairs of chromosomes found in the nucleus of each cell. Genes are inherited from parents, with one copy coming from each. This genetic information is passed down through generations, influencing not only physical characteristics but also aspects of health and behavior. Understanding human genes is essential for fields like genetics, medicine, and biotechnology.