DNA sequences are the specific order of nucleotides in a DNA molecule. Nucleotides are the building blocks of DNA and consist of a sugar, a phosphate group, and a nitrogenous base. The sequence of these bases—adenine (A), thymine (T), cytosine (C), and guanine (G)—determines the genetic information carried by an organism. Scientists analyze DNA sequences to understand genetic traits, evolutionary relationships, and disease mechanisms. Techniques like DNA sequencing allow researchers to read these sequences, providing insights into the functions of genes and the overall biology of organisms, including humans and other species.