Guru means teacher, master, or one who dispel darkness. Gurus were spiritual and social leaders for sikhs. There have been ten human Gurus but they had one light which is shabad guru. 1.) Guru Nanak - Guru from 1469 to 1539 2.) Guru Angad - Guru from 1539 to 1552 3.) Guru Amar Das - Guru from 1552 to 1574 4.) Guru Ram Das - Guru from 1574 to 1581 5.) Guru Arjan - Guru from 1581 to 1606 6.) Guru Hargobind - Guru from 1606 to 1644 7.) Guru Har Rai - Guru from 1644 to 1661 8.) Guru Harkrishan - Guru from 1661 to 1664 9.) Guru Tegh Bahadur - Guru from 1664 to 1675 10.) Guru Gobind Singh - Guru from 1675 to 1708 Every guru added something new to the community which made sikhi evolve over a course of 200+ years. Guru nanak said his guru is shabad. So before his passing, tenth guru passed the Guruship to the holy book / bani / shabad itself. SGGS is the central holy religious scripture of Sikhi. It is sovereign and eternal guru following the lineage of the ten human Gurus of the religion. The text consists of 1,430 angs (pages) and 5,894 shabads (line compositions), which are poetically rendered and set to a rhythmic ancient Indian classical form of music. The bulk of the scripture is divided into 31 main rāgas, with each rāga subdivided according to length and author. SGGS is written in the Gurmukhi script in various languages including Punjabi, Lahnda, regional Prakrits, Apabhramsa, Sanskrit, Braj Bhasha, Bangru, Awadhi, Old Hindi, Bhojpuri, Sindhi, Bengali, Persian, and Arabic. It was written and compiled but the Gurus themselves. It contains the teachings of six Gurus alongside many Bhakti movement saints such as Ramananda, Kabir and Namdev among others, and muslim Sufis such as Sheikh Farid. It also contains teachings by sikh Gurus to non-sikhs .SGGS covers multiple topics such as philosophy, human nature, enlightenment, mercy, ego, love, justice, etc.