In the 1900s the early European settlers in Africa killed 5 or 6 rhinos a day for sport or because they didn't like them.
In the 1960's it was noticed that the numbers were very low and so conservation groups helped to increase the numbers. But then between 1970 and 1992 96% of Africas rhinos were killed by poachers for their horns. Rhino horns can be sold for lots of money and some poor people in Africa need the horns for food and to live.
In 2010 one rhino was killed every day.