What is DNA sequencing?

Professor Allen Moore explains that the DNA code is a long sequence made up of four bases (A,C,T, and G) and DNA sequencing is the processes of identifying the order in which they occur.

DNA sequencing came about because the DNA code is made up of four different bases: A, T, C, and G. And so the question is 'when you have a different gene, what are the sequence of those bases?', and so you go through and actually identify whether its an A, a T, a C, or a G and you do that for the entire genome and then you have a genome sequence. So you can actually know the genetic makeup of an entire organism just by knowing those four bases, the order they occur in, and where they occur on a chromosome.