What is the name of Justin Bieber's debut single, released in 2009?

Explanation

Justin's single "One Time" was released on 18 May 2009. First mainstream and on the radio, and from 7 July onwards, via digital download in the US and Canada. In most other markets it was only released during the autumn of 2009. "One Time" became a huge hit and the then 15-year old went top 20 in Canada, the US, Germany, the UK, France and New Zealand. On 22 December the same year, Justin released "My Heart Edition" on iTunes. "My Heart Edition" is an acoustic version of "One Time".