The human Microbiome is made up of the 10-100 trillion symbiotic microbial cells that each person carries about with them, predominantly bacteria in the gut; the human microbiome is made up of the genes carried by these cells. Microbiome initiatives have been developed all over the globe in order to better understand the roles of these symbionts and their effects on human health. The description of the Human Microbiome has been hampered by terminology confusion: for example, the terms "microbiota" (microbial taxa associated with humans) and "microbiome" (a catalogue of these bacteria and their genes) are frequently interchanged. Furthermore, the word "metagenomics" was initially used to describe shotgun characterisation of whole DNA, but it is now increasingly being used to describe investigations of marker genes such the 16S rRNA gene.