DNA or deoxyribonucleic acid stores genetic information in the sequence of base pairs that span the helix like the rungs of a ladder.
The structure of DNA was elucidated over 50 years ago by James Watson and Francis Crick (see 1953 letter in NATURE). For this, they shared a Nobel Prize in 1962 with Maurice Wilkins (who, with Rosalind Franklin, furnished the X-Ray diffraction data).