The Ohio State University
A doctoral degree is the highest possible academic degree you can earn. Generally a Doctor of Philosophy (Ph.D.) is required if you want to teach at the college/university level or focus on advanced research in higher education or industry.
There are other types of doctoral degrees that are subject specific, such as a Doctor of Education (Ed.D.) or a Doctor of Musical Arts (DMA). These degrees have both a research and practical application component where you are required to demonstrate competency related to the field of study.
Typically, admission to a doctoral program comes with a guarantee of some funding. Many programs require a period of full-time study, and you can expect to spend between 3 and 6 years or more completing all degree requirements.