An eternal flame is a flame, lamp or torch that burns continuously for an indefinite period. Most eternal flames are ignited and tended intentionally, but some are natural phenomena caused by natural gas leaks, peat fires and coal seam fires, all of which can be initially ignited by lightning, piezoelectricity or human activity, some of which have burned for thousands of years.In ancient times,
eternal flames were fueled by wood or olive oil;[citation needed] modern examples usually use a piped supply of propane or natural gas. Human-created eternal flames
most often commemorate a person or event of national significance, serve as a symbol of an enduring nature such as a religious belief, or a reminder of commitment to a common goal, such as diplomacy.
The eternal fire is a long-standing tradition in many cultures and religions. In ancient Iran the atar was tended by a dedicated priest and represented the concept of “divine sparks”
or Amesha Spenta, as understood in Zoroastrianism. Period sources indicate that three “great fires” existed in the Achaemenid era of Persian history, which are collectively considered the earliest reference to the practice of creating ever-burning community fires.