Can you explain the origin of the name 'Sai Baba'? How did he come to be known by that title?

The name 'Sai Baba' was bestowed upon the spiritual master when he first arrived in Shirdi. As detailed in the introduction in Chapter 0, when he entered the Khandoba temple wearing a kafni, cap, and dhoti, a gentleman named Mhalasapati greeted him with the words 'Aavo Sai Baba,' which means 'Come, Sai Baba.' The master held onto this name for the rest of his life. It's noted in Chapter 0 that when his testimony was taken in a commission and he was asked his name, he simply replied, 'They call me Sai Baba,' affirming the name given to him by his devotee.