The Rhesus monkeys are the best to learn about the human body. The Anatomy and the physiology both of the Rhesus monkey match much fairly with that of the Humans. Therefore, scientists study Rhesus monkeys sometimes to study about the Human Anatomy. Once during the study of the Rhesus monkeys, certain blood proteins were found. These proteins were also found in some of the blood samples of the humans. However, this protein is not found in every blood sample. Hence, from then the presence of the protein, or the lack of it, is said to Rh (for Rhesus) factor.
The Rh-negative blood means that the blood without protein. It means that if our blood does not contain protein in it, then it is said to be Rh negative (Rh-) blood, where as the Rh-positive blood means that the blood with protein. It means that if our blood contains protein in it, then it is said to be Rh positive (Rh+) blood.
Hence, our blood types are connected to the Rh factors. We can have example like, if our blood is A+ which means that our A blood has positive Rh factor, meaning it consist of blood with A type antigen on its surface with the specific protein in it. Also another example is that we might have A- blood, which means that we have blood with negative Rh factor, meaning it consist of blood with B type antigen on its surface without the protein in it.