Kaur is a name used by Sikh women as either a middle or last name. The tenth guru of Sikhs, Guru Gobind Singh introduced Kaur and Singh, when he administered Amrit (baptism) to both male and female Sikhs. All female Sikhs were asked to use the name Kaur after their forename and male Sikhs were to use the name Singh. (Since 'Kaur' means "Princess", the name acts as a symbol of equality among men and women.) This custom further confirmed the equality of both genders as was the tradition set by the founder of Sikhism, Shri Guru Nanak Dev Ji. It was intended to give women a sense of self-respect and warrior ethos. Singh is also used by some non-Sikh women because Singh can be a last name for several other communities. It is the most common last name used by Sikhs. It is not mandatory to be baptized to include Kaur and Singh in the name.
Kaur provides Sikh women with a status equal to all men. This was also intended to reduce the prejudice created by caste-typing based on the family name. Prejudice based on caste was still rampant during Guru Gobind's time (17th century). This particularly affected women who were expected to take their husband's family name upon marriage. The British required women to take on their husbands' names.
Sikh principles believe that all men and women are completely equal. Therefore, a woman is crowned with great responsibility and can lead her own life as an individual, equal to men. She does not need a man's title to raise her own status. Saying this would go against the principles stated in the Sri Guru Granth Sahib, the religious text of Sikhism. Guru Nanak Dev Ji states:
Also, Gurbani (the text from Guru Granth Sahib) addresses every individual (irrespective of gender) as female. And combining from the above defined excerpt from Guru Granth Sahib  it can be easily concluded the temporal status of woman is higher than of man and they are equal only spiritually.
A section of around a million adherents of Sikhism who live abroad in western countries keep only Singh or Kaur as their last name. This has caused legal problems in immigration procedures, especially in Canada with the Canadian High Commission in New Delhi, India for a decade stating in letters to its Sikh applicants that "the names Kaur and Singh do not qualify for the purpose of immigration to Canada." People with these common Sikh surnames had to change their last names before coming to Canada. This had been causing emotional, legal and financial hardship for Sikh applicants in India who were complying by undergoing costly and lengthy name change procedures out of fear that their application to immigrate to Canada would be rejected outright otherwise. However, as soon as the media got involved and after a storm of complaints from Sikhs, Citizenship and Immigration Canada, Ottawa reversed New Delhi office's 10-year decree with Canadian Federal immigration officials further clarifying that "asking applicants to provide a surname in addition to Singh or Kaur has been an administrative practice used by our visa office in New Delhi as a way to improve client service and reduce incidents of mistaken identity. This was not a mandatory requirement. There is no policy or practice whereby people with these surnames are asked to change their names, the letters that were sent out to Sikh clients in Delhi were poorly worded."