The UniFrac system is a technique used to compare how similar two organisms share their phylogenetic information. In this process the two organisms are labeled either red or blue. The two are then compared each other using either a specifically colored shared branch or a specifically colored unshared branch leading to a specific taxon. The number of unshared branched are then divided by the total number of branches to find the distance between two taxa. The closer the number is to 0, the more similar the two taxa are to each other. The distance is only 0 when the two taxa are identical. This system satifies the distance metric.