The following table shows the flags and pennants typically used in U.S. Navy ships for visual signaling and gives basic explanations of their meanings. A comprehensive explanation of the meanings of these flags is far beyond the scope of this FAQ – the publications used to encode, decode, and interpret flag signals (the NATO Allied Tactical Publications – ATP-1A and B) comprise two binders, each about three inches thick!

In a formation one ship is designated the Guide, and all ships will take their stations relative to this vessel. The Guide flies the Golf flag. The Guide may or may not be the ship from which tactical (maneuvering) signals are sent. The Guide may change throughout an evolution or series of signals. All ships in company generally carry the Golf flag closed up (hoisted all the way to the yardarm) at the main, on centerline, but with the flag rolled up and tied with twine so that it cannot be seen. That way, if your ship is designated the Guide, all you do is give a sharp tug to the halyard, the twine breaks, the flag unfurls, and you're now the Guide. And you've looked sharp and seamanlike to boot.

A complete signal may comprise one or many flags. A limited number of flags can be accommodated on a single halyard, so a complete signal may take more than one halyard, but it is also possible to have more than one signal in a single hoist. One halyard of flags, whether a single flag or many, is called a hoist. When a signal must be broken into multiple hoists, it must be divided at such a point that the meaning is not changed. A complete signal or group of signals – whether on one hoist or on two or more adjacent hoists flying at the same time – is called a display. When displays of more than one hoist are raised, the separate hoists are run up, one by one, in the order they are to be read. A hoist of flags is always read from the top down; when multiple hoists are displayed, the signal is read top down, outboard to inboard, and from forward to aft. As a rule, a signal too long to be shown completely on three halyards is made into two or more displays. When two or more displays are used, the heading (the initial part of the signal) must be hoisted on a separate halyard and kept flying while successive displays are made. When several hoists are displayed simultaneously from different points, they are read in the following order: (1) masthead; (2) triatic stay (a line run between masts or from masthead to stack, etc.); (3) starboard yardarm; (4) port yardarm. Signals hoisted at yardarms of different heights are read beginning with the tallest.

A typical flag signal is raised at the dip (not fully raised up the halyards) by the ship which has the OTC (Officer in Tactical Command) embarked. All ships in the formation read the signal. Each ship's signals gang bends on exactly the same signal, and hoists it at the dip. This signifies that the ship has correctly read the signal (much embarrassment results if a ship hoists an incorrect version of the signal). As each receiving ship breaks (decodes) and understands the signal, it fully raises, or closes up, the hoist to show that it understands and is ready to carry out the orders and maneuvers implied by the signal. Once all receiving ships have closed up the signal, the OTC closes up the signal to indicate prepare to execute. Execution of the signal occurs when the OTC briskly hauls down the signal hoist.

Some flags have pretty obvious meanings, e.g. the Speed flag. Other flags, such as Corpen, can have many meanings depending on how it is used, where in the signal hoist it is found, what type of formation is currently in effect, etc. Some non-intuitive examples are given below:

• In its simplest usage, Corpen means course. The signal Mike Corpen Two Three Zero breaks as My course is two three zero degrees True. But Corpen Zero Niner Zero signals that a column of ships will turn in succession (as each reaches the point where the lead ship turned) to true course 090 (think of a column movement when marching, if that helps). Yet if you're in a different formation (not in a column), the meaning of the exact same signal is different. A carrier will signal Fox Corpen XXX, in which XXX degrees True is the planned course for flight operations (but don't you believe it – the carrier always lies, and will roar off in search of the flight deck wind it needs without necessarily telling you in advance, and woe betide if you find yourself in front of the birdfarm!).
• Similarly, Turn Starboard Niner breaks as a simultaneous turn by all ships, ninety degrees to starboard, yet Turn Starboard Zero Niner Zero breaks as a simultaneous turn to course zero nine zero degrees true, pretty much regardless what formation you are in.
• Designation (spoken Desig) is typically used to ascribe a name to something; for example, Echo X-ray Three Tack Three Desig Miller Time breaks as, Upon execution, commence exercise named Miller Time.
• Preparatory (called Prep) is used inport when getting ready for morning or evening colors. At the dip: 15 minutes prior. Closed up: 5 minutes prior. Hauled down: execute colors.
• Tack is not a flag at all, but a six-foot length of line with a snap hook on one end and a loop on the other (signal flags have the same snap and loop arrangement to permit quick attachment and detachment of a flag from a halyard). Tack is used to take up a signal flag-sized space in a hoist of flags. It separates two signals in one hoist, or it can represent a dash.

Signals from a ship to small craft can be made using the USN / NATO numeral eight flag, with modifiers as needed.

• Eight (flown alone) – Steer straight away from the ship.
• Eight flown with Port – Alter course to port. When the hoist is hauled down, cease turn and steady on course.
• Eight flown with Starboard – Alter course to starboard. When the hoist is hauled down, cease turning and steady on course.
• Eight flown with Screen – Steer straight toward the ship.

All this wonderful complexity exists for most of the non-numerical flags, thereby leading to the need for three-inch thick binders.

A ship when underway will usually display its international radio callsign in signal flags at all times.

There are international meanings for many of the alphabetic flags; these meanings may differ from standard USN usage. In these cases, both meanings are shown in the table below.