B.S

Means a Bachelor of Science. This degree means that the scientist went to college and studied a general area of science, like Biology or Math, for about four years . The area of science they studied follows the degree. So, if somebody has a B.S. in Geology, you know they graduated from a four-year college and studied geological science. By getting a B.S. degree you can sometimes get a job doing science, but people who want to do research usually go on to "graduate school" and get another degree....

M.S.

Means Master of Science. A scientist who has this degree went to graduate school, which usually takes from two to four years. While they were in graduate school they studied their area of interest in science in much greater detail, learning more specialized knowledge and learning how to do research. Sometimes, scientists want to get even more, highly specialized knowledge in their "field of study", so they can be leaders in the field of research science. They go on to get another degree....

Ph.D.

This means Doctor of Philosophy. Scientists who have this degree took anywhere from four to ten years to get it and are usually referred to by their title. For example, Indiana Jones is called Doctor Jones. The fictional character of Indiana Jones in the "Raiders of the Lost Ark" movie has his Ph.D. in Archaeological Science - the study of ancient human civilizations. Scientists who are called "Doctor" are not medical doctors, like the ones who take care of you when you're sick. Their title refers to the level of specialization and education that they have achieved in their field of study.