The Mool Mantar is the most important composition contained within the Sri Guru Granth Sahib, the holy scripture of the Sikhs; it is the basis of Sikhism. The word "Mool" means "main", "root" or "chief" and "Mantar" means "magic chant" or "magic portion".

Together the words "Mool Mantar" mean the "Main chant" or "root verse". It’s importance is emphasised by the fact that it is the first composition to appear in the holy Granth of the Sikhs and that it appears before the commencement of the main section which comprises of 31 Raags or chapters.

The Mool Mantar is said to be the first composition uttered by Guru Nanak Dev upon enlightenment at the age of about 30. Being the basis of Sikhism it encapsulates the entire theology of Sikhism. When a person begins to learn Gurbani, this is the first verse that most would learn.

It is a most brief composition encompassing the entire universally complex theology of the Sikh faith. It has religious, social, political, logical, martial and eternal implication for human existence; a truly humanitarian and global concepts of the Supreme power for all to understand and appreciate.

This Mantar encompasses concepts which have been evaluated and proven over many eras (or yugs) and known to be flawless beyond any ambiguity what so ever. The rest of Japji sahib that follows this mantar is said to be a elaboration of the main mantar and that the rest of the Guru Granth Sahib totalling 1430 pages, is a detailed amplification of the Mool Mantar.

This Mantar encompasses concepts which have been evaluated and proven over many eras (or yugs) and known to be flawless beyond any ambiguity what so ever. The rest of Japji sahib that follows this mantar is said to be a elaboration of the main mantar and that the rest of the Guru Granth Sahib totalling 1430 pages, is a detailed amplification of the Mool Mantar.

This is the verse that all beginners to Sikhism have to learn and repeat over and over again until it becomes an automatic process. After learning this short verse and its full meaning, it is common for beginners to awake early in the morning, wash and sit and mediate on the Mantar for 10 to 20 minutes focussing on the sound and meaning of each word.

It is said that the rest of the Guru Granth Sahib is an elaboration of the Mool Mantar and that this Mantar itself is an explanation and amplification of the single phrase – Ek Oankaar, which is the first entry in the holy Granth.

ੴ ਸਤਿ ਨਾਮੁ ਕਰਤਾ ਪੁਰਖੁ ਨਿਰਭਉ ਨਿਰਵੈਰੁ ਅਕਾਲ ਮੂਰਤਿ ਅਜੂਨੀ ਸੈਭੰ ਗੁਰ ਪ੍ਰਸਾਦਿ ॥
Meaning:
Ik- There is ONE(Ik) reality, the origin and the source of everything. The creation did not come out of nothing. When there was nothing, there was ONE, Ik.

Onkaar- When Ik becomes the creative principal it becomes Onkaar. Onkaar manifests as visible and invisible phenomenon. The creative principle is not separated from the created, it is present throughout the creation in an unbroken form, 'kaar'.

Satnaam- The sustaining principle of Ik is Satnaam, the True Name, True Name.

Kartaa Purakh- Ik Onkaar is Creator and Doer (Kartaa) of everything, all the seen and unseen phenomenon. It is not just a law or a system, it is a Purakh, a Person.

Nirbhau- That Ik Onkaar is devoid of any fear, because there is nothing but itself.

Nirvair- That Ik Onkaar is devoid of any enmity because there is nothing but itself.

Akaal Moorat- That Ik Onkaar is beyond Time (Akaal) and yet it is existing. Its a Form(Moorat) which does not exist in Time.

Ajooni- That Ik Onkaar does not condense and come into any birth. All the phenomenon of birth and death of forms are within it.

Saibhang- That Ik Onkaar exists on its own, by its own. It is not caused by anything before it or beyond it.

Gurprasaad- That Ik Onkaar is expresses itself through a channel known as Guru and it is only its own Grace and Mercy (Prasaad) that this happens.

Ik­oaʼnkār saṯ nām karṯā purakẖ nirbẖa­o nirvair akāl mūraṯ ajūnī saibẖaʼn gur parsāḏ.
One Universal Creator God. The Name Is Truth. Creative Being Personified. No Fear. No Hatred. Image Of The Undying, Beyond Birth, Self-Existent. By Guru's Grace

So the term used to describe this text from "Ek Onkar" to "Gur parsad" is called Mool Mantar while the slightly longer text from "Ek Onkar to "Nanak hosee bhee sach" is called Maha Mantar.

ੴ ਸਤਿ ਨਾਮੁ ਕਰਤਾ ਪੁਰਖੁ ਨਿਰਭਉ ਨਿਰਵੈਰੁ ਅਕਾਲ ਮੂਰਤਿ ਅਜੂਨੀ ਸੈਭੰ ਗੁਰ ਪ੍ਰਸਾਦਿ ॥
॥ ਜਪੁ ॥
ਆਦਿ ਸਚੁ ਜੁਗਾਦਿ ਸਚੁ ॥ ਹੈ ਭੀ ਸਚੁ ਨਾਨਕ ਹੋਸੀ ਭੀ ਸਚੁ ॥1॥

Transliteration:

Ik oa(n)kaar sath naam karathaa purakh nirabho niravair akaal moorath ajoonee saibha(n) gur prasaadh ॥
॥ jap ॥
aadh sach jugaadh sach ॥ hai bhee sach naanak hosee bhee sach ॥1॥

Alternative terminology:

Some consider the Mool mantar to be upto the text 'Nanak hosi bhi sach' as this appears only once in the beginning of the holy Granth while the "Manglaachran mantra" upto 'saibhng Gurparsad' appears 33 times in Sri Guru Granth Sahib.