I could summarize her story here but it's all over the internet and many writers have done a thorough job. One of the best articles I've read, was the New Yorker one, link here. If you're still interested after that then do check out the two documentaries about her, Finding Vivian Maier and the BBC's "Imagine" Vivian Maier: Who Took Nanny's Picture? Both are very different yet absorbing and ultimately sad. She died alone in Chicago never knowing that she would soon be hailed as the greatest street photographer of the 20th century.