DNA Structure

According to Wikipedia, Deoxyribonucleic acid (DNA) is a molecule that encodes the genetic instructions used in the development and functioning of all known living organisms and many viruses. 
Basically, DNA is our human code. It makes us, us. Every cell in our body has the same DNA in it. 

DNA is usually in a shape of a double helix, and has two strands running in opposite directions. (5' - 3', and 3' - 5')

There are 4 bases, Adenine, Thymine, Guanine, and Cytosine. A goes with T and G goes with C to form base pairs. Each base is connected to the sugar phosphate backbone.