The Nihang (Punjabi: ਨਿਹੰਗ) or Akali (lit. "the immortals") is an armed Sikh warrior order originating in the Indian subcontinent. Nihang are believed to have originated either from Fateh Singh and the attire he wore or from the "Akali" (lit. Army of the Immortal) started by Guru Hargobind. Early Sikh military history was dominated by the Nihang, known for their victories where they were heavily outnumbered. Traditionally known for their bravery and ruthlessness in the battlefield, the Nihang once formed the irregular guerrilla squads of the armed forces of the Sikh Empire, the Sikh Khalsa Army.
The word Akali/akaali means timeless or immortal.
Literally, one who belongs to Akaal (beyond Time). In other words, an Akaali is that person who is subject of none but God only. Conceptually speaking, the terms Akaali, Khalsa and Sikh are synonymous. The term Akaali was first used during the time of Guru Gobind Singh Sahib. The term Akaali became popular in the last decades of the eighteenth century.
The term came to be associated with “commitment, fearlessness, boldness, struggle, and justice.”
Nihang may come from the Persian word for a mythical sea creature (Persian: نهنگ). The term owes its origin to Mughal historians, who compared the ferocity of the Akali with that of crocodiles. The meaning of Akali in Sikhism however, is the immortal army of Akal (god).
Traditional Nihang dress is known as Khalsa Swarupa. This comprises full attire of superelectric blue selected by Guru Gobind Singh after conflicts with Vazir Khan, the Mughal Governor of Sirhind, edged bracelets of iron round their wrists (jangi kara) and quoits of steel (chakram) tiered in their lofty conical blue turbans, together with the traditional dagger carried by all Sikhs (kirpan). When fully armed a Nihang will also bear one or two swords (either the curved talwar or the straight khanda) on his right hip, a katar (dagger) on his left hip, a buckler made from buffalo-hide (dhala) on his back, a large chakram around his neck, and an iron chain. In times of war, arms worn on the Nihang's person would generally be reserved until the warrior lost the weapon he held, often a bow or spear (barsha). Armour consisted of sanjo or iron chainmail worn under an iron breastplate (char aina). Nihang war-shoes (jangi mozeh) were constructed of iron at the toe, making their pointed toes capable of inflicting cuts and stab wounds.
The Nihang were particularly known for their high turbans (dastar bunga) and their extensive use of the chakram or war-quoit. Their turbans were often pointed at the top and outfitted with a chand torra or trident called astbhuja which could be used for stabbing in close-quarters. Other times, the turbans would be armed with a bagh naka (iron claw) and one or several chakram to slice at an opponent's eyes. These steel-reinforced turbans, it was said, afforded enough protection so that there was no need for any other form of headgear. Today, Nihang still wear miniature versions of five weapons (pancha shastra) in their turbans, namely the chakram, the khanda (sword), the karud (dagger), the kirpan, and the tir (arrow).
Some Nihang groups consume cannabis or shaheedi degh (ਭੰਗ) , purportedly to help in meditation.  Sūkha parshaad (ਸੁੱਖਾ ਪ੍ਰਰਸਾਦ), "Dry-sweet", is the term Nihang use to refer to it. It was traditionally crushed and taken as a liquid, especially during festivals like Hola Mohalla. It is never smoked, as this practice is forbidden in Sikhism.
In 2001, Jathedar Santa Singh, the leader of Budha Dal, along with 20 chiefs of Nihang sects, refused to accept the ban on consumption of shaheedi degh by the apex Sikh clergy - in order to preserve traditional sikh practices. According to a recent BBC article, "Traditionally they also drank shaheedi degh, an infusion of cannabis, to become closer with God"
The Nihangs carry the original view of Sikhism and carry the original Nishan Sahib being plain Navy/electric blue and bright yellow or basanti attire. Yellow in Punjabi culture signifies sacrifice, revolt and honour while blue signifies courage, bravery and patriotism. Although in Punjab Blue is the colour of Khalsa and Yellow the colour of Kshatriyas the Gurus said that these are the colours of the casteless Khalsa.