The "Last Post" is either an A or a B♭ bugle call, primarily within British infantry and Australian infantry regiments, or a D or an E♭ cavalry trumpet call in British cavalry and Royal Regiment of Artillery (Royal Horse Artillery and Royal Artillery), and is used at Commonwealth military funerals, and ceremonies commemorating those who have died in war.

Its duration varies typically from a little over one minute to nearly three minutes.[ For ceremonial use, the "Last Post" is often followed by "The Rouse", or less frequently the longer "Reveille".

The two regimental traditions have separate music for the call. While the B♭ infantry bugle version is better known, the E♭ cavalry trumpet version is used by the state trumpeters of the Household Cavalry and Cavalry regiments of the line.

The "First Post" call signals the start of the duty officer's inspection of a British Army camp's sentry posts, sounding a call at each one. First published in the 1790s,[5] the "Last Post" call originally signalled merely that the final sentry post had been inspected, and the camp was secure for the night. In addition to its normal garrison use, the "Last Post" call had another function at the close of a day of battle. It signalled to those who were still out and wounded or separated that the fighting was done, and to follow the sound of the call to find safety and rest.

Its use in Remembrance Day ceremonies in Commonwealth nations has two generally unexpressed purposes: the first is an implied summoning of the spirits of the Fallen to the cenotaph, the second is to symbolically end the day, so that the period of silence before the "Rouse" is blown becomes in effect a ritualised night vigil. The "Last Post" as sounded at the end of inspection typically lasted for about 45 seconds; when sounded ceremonially with notes held for longer, pauses extended, and the expression mournful, typical duration could be 75 seconds or more.

This custom dates from the 17th century or earlier. It originated with British troops stationed in the Netherlands, where it drew on an older Dutch custom, called taptoe, from which comes the term tattoo as in Military tattoo. The taptoe was also used to signal the end of the day, but originated from a signal that beer taps had to be shut, hence that the day had ended. It comes from the Dutch phrase Doe den tap toe, meaning "Close the tap". The Dutch bugle call Taptoesignaal, now used for remembrance events, is not the same tune as the "Last Post".

The "Last Post" was used by British forces throughout North America in colonial times. In the United States it was replaced by the different "Taps" by the United States Army, first used in 1862 and officially recognized in 1874.