Seaman is the third lowest enlisted rate in the U.S. Navy and other navies. For the U.S. Navy and U.S. Coast Guard the rate is just above Seaman Apprentice and below Petty Officer Third Class; this rate was formerly known as Seaman First Class.

The actual title for an E-3 in the U.S. Navy varies based on the community to which the sailor belongs. Likewise, the color of their group rate marks also depends on their community.

• Those in the general deck and administrative community are Seamen. They wear White stripes on navy blue uniforms, and navy blue (black) stripes on white uniforms.
• Hospital Corpsmen are Hospitalmen. They are the only rate in this community. They wear White stripes on navy blue uniforms, and navy blue stripes on white uniforms.
• Those in the engineering and hull community are called Firemen and wear red stripes on both navy blue and white uniforms.
• Those in the aviation community are called Airmen and wear green stripes on both navy blue and white uniforms.
• Seabees are called Constructionmen and wear light blue stripes on both navy blue and white uniforms.

No stripes are worn on the working uniforms - coveralls or utilities.

In October 2005, the Dental Technician rating was merged with the Hospital Corpsman rating, eliminating the Dentalman title. Those who once held the rank of Dentalman have instead become Hospitalmen.

Sailors who have completed the requirements to be assigned a rating and have been accepted by the Bureau of Naval Personnel as holding that rating (a process called "striking") are called Designated Strikers, and are called by their full rate and rating in formal communications (ie, Machinist's Mate Fireman, as opposed to simply Fireman), though the rating is often left off in informal communication. Those who have not officially been assigned to a rating are officially referred to as "Undesignated" or "Non-rates."