There are 5 species of rhino in the world - White, Black, Greater One horned, Javan and Sumatran. These are divided into a total of 11 sub species. Its estimated that the total population of all five species combined is about 27,000.
Some are on the very brink of extinction. There are for example an estimated 75 Javan rhino left alive and about 80 Sumatran. The Greater one horned rhino is found in India and Nepal and has stable numbers of about 4,000. Black and white rhino are found in Africa, with c. 6,000 of the former and 16,000 of the latter.
There are many organisations dedicated to saving the rhino, including explorersagainstextinction.co.uk who campaign against species extinction and habitat loss worldwide.