The carbon atoms on the sugar are given prime numbers: 1' through 5'.
The nitrogenous base is either a pyrimidine - Cytosine (C), Thymine (T), and Uracil (U) - or a purine - Adenine (A) and Guanine (G).
Thymine is found in DNA (Deoxyribonucleic Acid), while Uracil is found in RNA (Ribonucleic Acid).