Shanghaiing or crimping is the practice of kidnapping people to serve as sailors by coercive techniques such as trickery, intimidation, or violence. Those engaged in this form of kidnapping were known as crimps. The related term press gang refers specifically to impressment practices in the United Kingdom's Royal Navy.

Impressment, colloquially "the press" or the "press gang", is the forced conscription of men into a military force, especially a naval force, via intimidation and physical coercion, conducted by an organized group. European navies of several nations used forced recruitment by various means. The large size of the British Royal Navy in the Age of Sail meant impressment was most commonly associated with Great Britain and Ireland. It was used by the Royal Navy in wartime, beginning in 1664 and during the 18th and early 19th centuries as a means of crewing warships, although legal sanction for the practice can be traced back to the time of Edward I of England. The Royal Navy impressed many merchant sailors, as well as some sailors from other, mostly European, nations. People liable to impressment were "eligible men of seafaring habits between the ages of 18 and 55 years". Non-seamen were sometimes impressed as well, though rarely. In addition to the Royal Navy's use of impressment, the British Army also experimented with impressment from 1778 to 1780.