There are multiple different certification levels that can be obtained from multiple different certifying bodies. The most widely accepted certifications are from PADI, although most dive shops also honor certifications from SSI, CMAS, NAUI, and more. Each certifying body has individual different levels of certification, but in general, shops usually honor certifications based on the following levels.
As a beginner, the student learns to manage him or herself and their equipment in the water. Beginner certifications include:
As a diver gets more experience, the diver begins to focus on their interactions with their environment, with improved skills in buoyancy control, gas usage, navigation, and more. Advanced certifications include:
The three main skills courses to do at the early part of advanced diving revolve around "deep" diving to 30m, perfecting buoyancy, and navigation. Many people get an introductory taste of wreck diving and cavern diving in their advanced certification, but this should not be confused with wreck penetration and cavern certifications, which are completely separate skills courses.
The higher end of Advanced diving, as well as technical diving, introduces additional challenges and skills not commonly found with recreational divers. Useful advanced and technical certifications include:
The start of becoming a dive professional usually starts with become a certified rescue diver. This certification is typically regarded as a title only, as one can start it with a shockingly low amount of dives. The skills primarily revolve around the diver learning to not only be responsible for themselves, but for others in the water, and how to rescue them if necessary. Many people seeking to become a dive professional just lump this into the Dive Master certification.
Dive Masters lead groups and plan dives in detail.
Reaching the higher levels of professional dive careers, these divers learn to teach, test, and certify other divers.