The founder of Sikhism is Guru Nanak Dev Ji, who was born in 1469 in the village of Talwandi in present-day Pakistan. He was the first of ten Gurus who established and spread the teachings of Sikhism.

Guru Nanak Dev Ji was a spiritual leader who rejected the rituals and superstitions of the existing religions of his time and instead focused on the importance of devotion to one God and service to humanity. He believed in the equality of all humans regardless of caste, gender, or social status.

At the age of 30, Guru Nanak Dev Ji had a profound spiritual experience that shaped his teachings and led him to travel extensively to spread his message. He traveled to various parts of India, as well as to Mecca and Baghdad, engaging in discussions with both Hindu and Muslim leaders.

During his travels, Guru Nanak Dev Ji emphasized the concept of "Ik Onkar," which means "One God." He believed that there is only one God, who is formless, all-pervading, and can be reached through meditation and selfless service. He also stressed the importance of living a moral and ethical life, and treating others with compassion and kindness.

Guru Nanak Dev Ji also established the concept of "Sangat" or community, where people could come together to worship, learn, and serve others. This community aspect of Sikhism continues to be an integral part of the religion today.

After Guru Nanak Dev Ji's passing, his teachings were compiled by his successor, Guru Angad Dev Ji, into a sacred text known as the Guru Granth Sahib. This text is considered the living Guru of the Sikhs and is the source of spiritual guidance for the community.

In conclusion, Guru Nanak Dev Ji is considered the founder of Sikhism for his revolutionary teachings that emphasized devotion to one God and service to humanity. His message of equality, compassion, and community continues to inspire millions of Sikhs around the world and remains relevant in today's world.