The three most important and well-documented wives of Akbar are Ruqaiya Sultan Begum, Salima Sultan Begum, and Mariam-uz-Zamani. Not much is known about his other wives.
Ruqaiya Sultan Begum, born in 1542, was Akbar's first wife. Their wedding took place in 1551, making both her and Akbar only 9 years old when they were married. She was Akbar's first cousin and served for 49 years as Mughal empress.
Salima Sultan Begum married Akbar in 1561. She was first cousin to both Akbar and his first wife Rugaiya, and was nearly four years older than they were. We have Salima to thank for much of the information from Akbar's reign, as she was a keen record-keeper.
Mariam-uz-Zamani married Akbar in 1562. Mariam-uz-Zamani was the mother of Akbar's heir, Jahangir. It is likely that she was the closest to Akbar, as she was the only wife buried near her husband after their deaths. She is often referred to by the name Jodha Bai, but this name was not used until the 18th or 19th Century. Jodha Bai may actually have been another name for the wife of Jahangir, Taj Bibi Bilqis Makani.
Akbar, or Akbar the Great, was Mughal Emperor from 1556 to 1605, and is believed to have had 36 wives.