Part 61 is the counterpart to Part 91. Being a part of the Federal Aviation Regulations or FARs, Part 61 deals with the licensing and certification of pilots who are attempting a single, multi, or commercial license. It also defines the certification of flight instructors, ground instructors, airline transient pilots, and student pilots. Part 61 is a why of teaching how to fly. Like all the other chapters in the FARs Part 61 has its own rules and requirements that must be met and followed in order to successfully complete training. It gives detailed prerequisites for getting your licenses. In fact one of the few things not covered in Part 61 is the certification of pilots for instrument flight, or IMC certification.
Unlike Part 91, Part 61 does not deal with the standards of the charter or airline operations for aircraft but instead deals with requirements for the pilots flying those aircraft, although charter and airline pilots can originate from a Part 61 school. Part 61 is no less then dedicated to the standards of human performance in aviation where as Part 91 also incorporates standards for companies and their aircraft. Schools might choose to teach Part 61 or Part 91 because of less stringer standards. However, there are more time requirements for Part 61. Smaller flight schools not associated with universities or colleges will probably be teaching under Part 61 due to the freedom it gives to teach. It allows for smaller business to share the flying experience with future pilots without have to possess the creditability of a university such as Embry Riddle Aeronautical University in Daytona Beach.
There are colleges however that operates under Part 61 though few and far between. Daniel Webster College in Nashua, NH is a Part 61 operating college. They run a program that is more lax and deal strictly with the certification of pilots. Since instrument flying is not covered in Part 61 it is not taught at Daniel Webster.
Along with pilot ratings, one can receive helicopter ratings, rotorcraft ratings, balloon ratings, crop dusting ratings, tail wheel plane endorsements, and a recreational pilots license. It also covers things like second in command requirements and category II and III aircraft certification as well as required certificates and logbook endorsements.