United States Coast Guard ratings are general occupations that consist of specific skills and abilities. Each rating has its own specialty badge, which is typically worn on the left sleeve of their service dress uniform by all enlisted personnel in that particular field. On Operational Dress Uniforms, they wear generic rate designators that exclude the rating symbol. Commissioned Officers do not have ratings.
Ratings should not be confused with "rates", which describe the Navy's and Coast Guard's enlisted pay-grades. Enlisted Navy and Coast Guardsmen are referred to by their rating and rate. For example, if someone's rate is Petty Officer 2nd Class and his rating is Boatswain's Mate; when combined, Boatswain's Mate 2nd Class (BM2) defines both. More examples are listed in the table below.
The AMT inspects, services, maintains, troubleshoots and repairs aircraft power plant, power train and structural systems. The AMT maintains metal, composite and fiberglass materials, fabricates cables, wire harnesses and structural components; and performs aircraft corrosion control, nondestructive testing, basic electrical troubleshooting and record keeping. Additionally AMTs also hold an aircrew position in specific Coast Guard aircraft
The Aviation Survival Technician inspects, services, maintains, troubleshoots and repairs aircraft and aircrew survival equipment and rescue devices. Additionally, ASTs perform the duties of a rescue swimmer and provide aircrew survival training to all aviators.
Inspects, services, maintains, troubleshoots and repairs aircraft power, communications, navigation, auto flight and sensor systems. AETs perform minimum performance checks, system alignments, avionics corrosion control and record keeping. Additionally, AETs hold an aircrew position in specific Coast Guard aircraft.
MSTs conduct marine-safety activities such as investigating pollution incidents, monitoring pollution cleanups, conducting foreign-vessel boardings to enforce pollution and navigation safety laws, conducting harbor patrols for port safety and security, inspecting waterfront facilities and supervising the loading of explosives on vessels. Most are assigned to shore-based field units such as sectors. They may be assigned to the National Strike Force for oil and hazardous-material response. MSTs are also the Coast Guard’s safety and environmental health experts ashore.
The musician rating in the Coast Guard is restricted to members of the Coast Guard Band which is located at the U.S. Coast Guard Academy in New London, CT. The United States Coast Guard Band recruits only the most highly skilled musicians, and the audition process is extremely competitive. The Director makes the final decision to award the position to the winner(s) who then enlist in the United States Coast Guard for a period of four years at the rank of Musician First Class (E-6).
Operates small boats; stores cargo; handles ropes and lines; and directs work of deck force. Performs navigation of ship's steering; lookout supervision, ship control, bridge watch duties, visual communication and maintenance of navigational aids. The most versatile rating in the Coast Guard, and the only rating that can lead to a command position. (This rating is a combination of the previous USCG ratings of Quartermaster and Boatswain's Mate).
Serve as specialist in maritime law enforcement and security. The rate was officially established January 1, 2010 when 1,053 active duty and 988 reserve members transitioned from existing rates and became maritime enforcement specialists. The new rating is designed to enhance the Coast Guard's capabilities as America’s maritime guardians and support the Coast Guard’s modernization goal of developing a force structure responsive to mission execution.
Intelligence Specialists are involved in collecting and interpreting intelligence, especially about enemies or potential enemies. They analyze photographs and prepare charts, maps, and reports that describe in detail the strategic situation all over the world.
Fabricates, installs and repairs shipboard structures, plumbing and piping systems; uses damage control in fire fighting; operates nuclear, biological, chemical and radiological defense equipment; construction work.
Tests, maintains and repairs electrical equipment including navigation, identification, detection, reconnaissance, special purpose equipment and conducts electrical training for all MK's throughout the fleet; operates warfare equipment.
Note: Electrician's Mates don't work on avionics. It's all shipboard maintenance and residential electrical work. 
Maintains all electronic equipment used for communications, detection ranging, recognition and countermeasures, worldwide navigational systems, computers and sonars. ET's Also maintain towers and antennas.
Note: Electronics Technicians are normally part of the Operations Department, not Engineering. They also do the jobs that were once done by the Fire Control Technicians, including maintaining and operating the fire control radars, and firing the major weapons systems on the boat including the 76 MM cannon and the CWIS anti-ship missile defense system.
Operates communication equipment; transmits, receives and processes all forms of military record and voice communications. Installs and maintains telecommunications equipment ranging from pole lines and underground cables to computer-based data communications and processing systems, telephone and data switching systems and networks, and public address, security and remote control systems
Provide support to Coast Guard law-enforcement and intelligence missions. Conduct both criminal and personal background checks and investigations, collect and analyze intelligence information and provide personal protection services to high-ranking Coast Guard officials and other VIPs.
Support of Department of Defense national-defense operations overseas as a member of a Naval Coastal Warfare Squadron, or a Coast Guard Port Security Unit. Work at a Sector to ensure the physical security of a major U.S. port, or be a member of a Maritime Safety and Security Team (MSST). MSSTs are capable of being deployed throughout the United States to provide heightened waterside and shoreside security in support of maritime homeland security operations.
These two rating no longer exist. RMs where converted to TCs in 1995. The TC rating was then disestablished in 2003; 75% of the workforce moved to the OS rating and the remaining 25% moved to the IT rating.