If you want to attain the highest level of achievement possible in one of many different academic fields, you'd have to earn a doctorate degree. A PhD, or Doctor of Philosophy degree, is awarded by university faculty to students who have made significant contributions to a particular field. This significant contribution usually is a large doctoral thesis or dissertation, which generally has to be defended by the student in front of a faculty committee before the student can earn the degree. There are mainly three types of doctorates awarded from universities and colleges: research, first-professional (U.S. only), and honorary.
Those who earn doctorate degrees generally use the title of "doctor" in academic environments or in publication. The use of PhD as a written suffix for anyone who has earned a doctorate degree is common practice. The "Doctor of Philosophy" title is merely traditional, and applies to most doctoral graduates, even if they are in a field not related to philosophy.
To receive a doctorate in most fields, students have to prove that they've earned a bachelor's degree, or a bachelor's and master's degree. The requirements vary by field. As a rule of thumb, those looking to become physicians, lawyers, dentists, or chiropractors aren't generally required to hold masters degrees before working on their doctorate. Other more academic fields will often require both the bachelor and graduated degree.
How Long Does it Take?
At this level, the time it takes to complete a doctorate is generally up to the students. Most doctoral students, however, take at least three years to complete their studies. Some students spend up to eight years chipping away at their degrees. Most college professors are required to have a PhD, as well as most high level scientific researchers. The degree requirements for medical and law students looking to earn MDs or JDs (Juris Doctor, the most common law school degree) varies by institution.