Thymine

Thymine, or 5-methyluracil, is a pyrimidine base found in the nucleic acid DNA.

In RNA thymine is swapped for uracil to represent the same genetic information.  In DNA, thymine (T) connects to adenine (A) by two hydrogen bonds. These pair bonds hold the two strands of the DNA double helix structure together.

 Other websites 
 Computational Chemistry Wiki 

Category:Pyrimidones
Category:DNA