In Sikhism, Guru is the source of all knowledge which attributed to Almighty by Guru Gobind Singh in Chopai Sahib:
ਜਵਨ ਕਾਲ ਸਭ ਜਗਤ ਬਨਾਯੋ ॥ ਦੇਵ ਦੈਤ ਜੱਛਨ ਉਪਜਾਯੋ ॥
जवन काल सभ जगत बनायो ॥ देव दैत ज्छन उपजायो ॥
The Temporal Lord, who created the whole world; who created gods, demons and yakshas;
ਆਦਿ ਅੰਤਿ ਏਕੈ ਅਵਤਾਰਾ ॥ ਸੋਈ ਗੁਰੂ ਸਮਝਿਯਹੁ ਹਮਾਰਾ ॥੩੮੫॥
आदि अंति एकै अवतारा ॥ सोई गुरू समझियहु हमारा ॥३८५॥
He is the only one form the beginning to the end; I consider Him only my Guru.385.
The Sikh Gurus established Sikhism over the centuries, beginning in the year 1469. Sikhism was founded by the first guru, Guru Nanak, and subsequently, each guru, in succession, was referred to as "Nanak", and as "Light", making their teachings, in the holy scriptures, equivalent. There are a total of 11 gurus, of which the current and everlasting Sikh Guru is the integrated Sikh scriptures known as the Adi Granth or Guru Granth Sahib.
Sikhism was established by Guru Nanak and ten other Sikh Gurus starting in 1469. Guru Nanak was the first Guru, and Guru Gobind Singh, the 10th Guru, bestowed the Guruship forevermore to the Sikh holy scripture, the Guru Granth Sahib as the 11th Guru, the living word. The Khalsa is known as the Guru Panth, the final temporal Guru/leader of the Sikhs and embodiment of the Guru. Sikhs follow the teachings of the Gurus, which is believed upon remembering, leads to salvation.
The name "Nanak" was used by all the subsequent Gurus who wrote any sacred text in the Sikh holy scripture called the Guru Granth Sahib. The second Sikh Guru, Guru Angad, is also called the "Second Nanak" or "Nanak II". Sikhs hold that all subsequent Gurus carried the same message as that of Guru Nanak, and so they have used the name "Nanak" in their holy text, instead of their own names. Hence all are referred to as the "Light of Nanak".
|#||Name||Date of birth||Guruship on||Date of ascension||Age|
|1||Guru Nanak||15 April 1469||20 August 1507||22 September 1539||69|
|2||Guru Angad||31 March 1504||7 September 1539||29 March 1552||48|
|3||Guru Amar Das||5 May 1479||26 March 1552||1 September 1574||95|
|4||Guru Ram Das||24 September 1534||1 September 1574||1 September 1581||46|
|5||Guru Arjan||15 April 1563||1 September 1581||30 May 1606||43|
|6||Guru Har Gobind||19 June 1595||25 May 1606||28 February 1644||48|
|7||Guru Har Rai||16 January 1630||3 March 1644||6 October 1661||31|
|8||Guru Har Krishan||7 July 1656||6 October 1661||30 March 1664||7|
|9||Guru Tegh Bahadur||1 April 1621||20 March 1665||11 November 1675||54|
|10||Guru Gobind Singh||22 December 1666||11 November 1675||7 October 1708||41|
|11||Guru Granth Sahib||n/a||7 October 1708||n/a||n/a|