The way I understand it, genes are rather sparse within a strand of DNA. The human genome, for example, has a few thousand genes in a strand of 3.5 million A,C,G,T bases. I also understand that genes code for proteins through RNA but, again, most of the DNA is noncoding. My question is, how do we identify genes from non-genes? I've searched through google and found some useful sites, such as this one http://www.genomenewsnetwork.org/articles/06_00/sequence_primer.shtml but they are overly complex for my question. I'm impressed that the entire genome can be decoded, but is there a simple explanation for how a geneticist identifies that this particulare section of DNA is a gene and that one is not?