Getting into a doctoral program can require quite a bit of work and the program itself can be grueling. Once you're enrolled in a Ph.D. program, you'll be expected to demonstrate basic knowledge about your field, teach beginning students, conduct research and contribute novel knowledge to the field in the form of a dissertation. In the midst of all of this stress, you may wonder what the point of all the work is, but a Ph.D. serves as certification that you have become an expert in your field.
A doctoral degree certifies you as an expert in your chosen field or in a particular niche within your chosen field. Most doctoral students have to take rigorous qualifying exams, demonstrating knowledge of a wide variety of concepts. You'll also have to take intense, graduate-level classes, produce high-quality papers and discuss challenging concepts with your professors and academic advisor. Many doctoral programs have very high minimum grade requirements precisely because people granted doctorates must truly be experts.
To complete your doctoral program, you'll have to write, defend and publish a dissertation. Your dissertation should present new research or concepts to the field. You might develop a new computer program, invent a design, develop a novel analysis of philosophy or literature or address potential new treatments for mental disorders. This process contributes new knowledge to the field and opens up new avenues for future research. Some people with doctoral degrees devote their entire careers to the topics they discussed in their dissertations.
Many students in doctoral programs teach introductory-level classes, which means that a Ph.D. program provides a university with a ready supply of instructors. Additionally, to become a tenure-track professor, you'll generally need a doctoral degree. Your years spent teaching as a graduate student plus the expertise you developed in the process of becoming a doctor can help you attain an academic post.
A Ph.D. lends credibility to your ideas and gives you access to research projects and funding. It's much harder to gain credibility without the educational credentials to back it up, and a Ph.D. after your name tells potential employers, government grant givers and research professionals that you have the requisite skills to complete your projects and provide insight into your chosen field.