A SNP is a variation of a single nucleotide between individuals. These polymorphisms can therefore be used to discern small differences both within a population and among different populations.
President of the United States. The President of the United States is the head of state of the U.S., the chief executive of the federal government, and Commander-in-Chief of the armed forces. The United States was the first nation to create the office of President as the head of state in a modern republic.
John Hanson. When we think of the President of the United States, many people do not realize that we are actually referring to presidents elected under the U.S. Constitution. Everybody knows that the first president in that sense was George Washington.