The main component of DNA is the nucleotide, which consists of three parts: a phosphate group, a deoxyribose sugar, and a nitrogenous base. DNA is structured as a double helix, with nucleotides linked together by covalent bonds forming the backbone and paired through hydrogen bonds between complementary bases (adenine with thymine, and cytosine with guanine). This unique structure enables DNA to store and transmit genetic information essential for cellular functions, heredity, and the synthesis of proteins, ultimately influencing an organism's traits.