Sea shanties (singular "shanty", also spelled "chantey"; derived from the French word "chanter", 'to sing') were shipboard working songs. Shanties flourished from at least the fifteenth century through the days of steam ships in the first half of the 20th century. Most surviving shanties date from the nineteenth and (less commonly) eighteenth centuries.

In the days when human muscles were the only power source available aboard ship, sea shanties served a practical purpose: the rhythm of the song served to synchronize the movements of the shipworkers as they toiled at repetitive tasks. They also served a social purpose: singing, and listening to song, is pleasant; it alleviates boredom, and lightens the burden of hard work, of which there was no shortage on long voyages.

Most shanties are "call and response" songs, with one voice (the shantyman) singing the line and the chorus of sailors bellowing the response (compare military cadence calls). For example, the shanty "Boney":
 

Shantyman:	Boney was a warrior,
All:	Way, hey, ya!
Shantyman:	A warrior and a terrier,
All:	Jean-François!
The crew would then pull on the last syllable of the response in each line

Categories

Shanties may be divided into several rough categories:

Short Drag Shanty	Short drag or short haul shanties were for tasks that required quick pulls over a relatively short time, such as shortening or unfurling sails. When working in rough weather these songs kept the sailors in a rhythm that got the job done safely and efficiently.
Long Drag Shanty	Long drag or halyard shanties were for work that required more setup time between pulls. It was used for heavy labour that went on for a long time, for example, raising or lowering a heavy sail. This type of shanty gave the sailors a rest in between the hauls, a chance to get a breath and a better grip, and coordinated their efforts to make the most of the group’s strength for the next pull. This type of shanty usually has a chorus at the end of each line.
Capstan Shanty	Capstan (or windlass) shanties were used for long or repetitive tasks that simply need a sustained rhythm. Raising or lowering the anchor by winding up the heavy anchor chain was their prime use. This winding was done by walking round and round pushing at the capstan bars, a long and continuous effort. These are the most developed of the work shanties.
Pumping Shanties	All wooden ships leak somewhat. There was a special hold (cargo area) in the ships where the leaked-in water (the bilge) would collect: the bilge hold. The bilge water had to be pumped out frequently; on period ships this was done with a two-man pump. Many pumping shanties were also used as capstan shanties, and vice versa, particularly after the adoption of the Downton pump which used a capstan rather than pump handles moved up and down. Examples include: "Strike The Bell", "Shallow Brown", "Barnacle Bill the Sailor", "Lowlands".
Forecastle Shanties	In the evening, when the work was done, it was time to relax. Singing was a favored method of entertainment. These songs came from places visited, reminding the sailors of home or foreign lands. Naturally the sailors loved to sing songs of love, adventure, pathos, famous men, and battles. Of course after all the hard work just plain funny songs topped their list.
Stamp-'n'-Go Shanties	These were used only on ships with large crews. Many hands would take hold of a line 'tug-of-war' style and march away along the deck singing and stamping out the rhythm. Alternatively, with a larger number of men, they would create a loop -- marching along with the line, letting go at the 'end' of the loop and marching back to the 'top' of the loop to take hold again for another trip. These songs tend to have longer choruses similar to capstan shanties. Examples: "Drunken Sailor", "Roll the Old Chariot". Stan Hugill, in his Shanties from the Seven Seas writes: "(Drunken Sailor) is a typical example of the stamp-'n'-go song or walkaway or runaway shanty, and was the only type of work-song allowed in the King's Navee (sic). It was popular in ships with big crews when at halyards; the crowd would seize the fall and stamp the sail up. Sometimes when hauling a heavy boat up the falls would be 'married' and both hauled on at the same time as the hands stamped away singing this rousing tune."
Whaling Shanties	Life on a whaler was worse than on any other type of vessel; your life might be shorter on a pirate’s ship, but the work wouldn't be so hard! Voyages typically lasted from two to three years, and sailor’s lives were filled with unrelenting, dangerous work and the ever-present stench of whale oil. Whalers risked maiming and death when giving chase in small boats that were often overturned or even smashed by the whale’s tail in the fight! Songs helped give these men the will to go on in the face of their ful circumstances.

Of course, the above categories are not absolute. Sailors could (and did) take a song from one category and, with necessary alterations to the rhythm, use it for a different task. The only rule almost always followed was that songs that spoke of returning home were only sung on the homeward leg, and songs that sung of the joys of voyaging etc., were only sung on the outward leg. Other songs were very specific. "Poor Old Man" (also known as "Poor Old Horse" or "The Dead Horse") was sung once the sailors had worked off their advance (the "horse") a month or so into the voyage. "Leave Her, Johnny Leave Her" (also known as "Time for Us to Leave Her") was only sung during the last round of pumping the ship dry once it was tied up in port, prior to leaving the ship at the end of the voyage.

The shantyman

The shantyman was a sailor who led the others in singing. He was usually self-appointed. A sailor would not generally sign on as a shantyman per se, but took on the role in addition to their other tasks on the ship. Nevertheless, sailors reputed to be good shantymen were valuable and respected — it was a good professional skill to have, along with strong arms and back.

Performance of shanties

Historically, shanties were usually not sung ashore. Today, they are performed as popular music. Shanty choirs, often large choral groups that perform only sea shanties, are popular in Europe, particularly Poland and the Netherlands, but also countries such as Germany and Norway. In English-speaking countries, sea shanties are comparatively less popular as a separate genre and tend to be performed by smaller groups as folk music rather than in a choral style. They are also sung by some folk music clubs as a social pastime, not for performance. A medley of sea shanties performed by classical orchestra, Sir Henry Wood's Fantasia on British Sea Songs, is a popular component of the Last Night of the Proms in Britain.

Although the "days of the tall ships" are over, the shanty song style is still used for new musical compositions. Well known examples include the Stan Rogers song, "Barrett's Privateers," the Steve Goodman song, "Lincoln Park Pirates," and the theme song for the television show SpongeBob SquarePants (a version of "Blow the Man Down"). Even the song "Reise, Reise" by the German Tanz-Metall band Rammstein is based on a shanty, "Reise, Reise."