A Doctor of Philosophy is the highest degree that is awarded
You can call me "Doctor," but I'm not a Medical Doctor. (M.D.) In the case of a Ph.D., "Doctor" comes from the Latin word meaning "to teach."
You can see what Wikipedia has to say about it here.
There is a LOT of pomp and circumstance and general snob factor and annoying puffiness.
But basically, it means graduating from something like the 25th grade.
Having a Ph.D. is not quite as exclusive a club as you might think. About 2% of the U.S. population has some sort of Doctorate. A Ph.D. does not mean that you are the smartest person in the room. There are plenty of brilliant people who have never graduated from college.
Mostly, a Ph.D. indicates that you have the interest, determination, and work ethic to put up with years of academic work before seeing any tangible results. It indicates that you are a self-starter, and have been successful at navigating the obscure domains of research funding, academic publication, and administrative rules.
Basically, a Ph.D. is your ticket to get in the door if you want to work as an Academic or Researcher.
The attrition rate (folks who quit their Ph.D. for one reason or another) is around 50%. Everyone who pursues a Ph.D. faces seemingly insurmountable obstacles and outright hostility at some point during the process. The key to success is the creativity, determination, endurance, and hard work to get through the people and things who try to stop you - and there will be plenty of hostile people and things that try to stop you. It is critical to success to have a very good and supportive committee of mentors.
One thing that became very apparent to me as I pursued the degree:
A Ph.D. is an apprenticeship.
No one is an island. A Ph.D. is a team effort between the student and their mentors and their whole support network. Without a doubt, the single, most important factor in a Ph.D. is the choice of the Committee of Mentors. Everyone with a Ph.D. will be quick to name their mentors, and to give credit to the lineage of those who helped them succeed in their work. We are all standing on the shoulders of giants.
My Ph.D. is in the field of Computer Engineering. I worked with Dr. Frank Skidmore, a Neurologist, and a bunch of other really smart people. I did a lot of Research work in the field of brain imaging and non-linear deformation mapping and Tensor Based Morphometry. I came up with some new deformation metrics and computation techniques that had not been done before. Then I wrote some software to do all of this exciting math and used our high-performance computers to analyze a few hundred brain images and showed that these techniques were useful for finding diseased areas in the brain.
The title of my dissertation is:
My entire committee is listed below, but I am especially grateful to Dr. Tanik and Dr. Skidmore for their longsuffering and mentorship throughout the entire process, and to Dr. Vaughn for his guidance over many decades.
Gregg L. Vaughn, Ph.D. (Chair)
Murat M. Tanik, Ph.D. (Co-Chair)
Gregory A. Franklin, Ph.D.
Frank M. Skidmore, M.D.
B. Earl Wells, Ph.D.