Why do variable names often start with the letter 'm'?

Looking at the Android tutorials such as the Notepad tutorial, I noticed that almost all variables are named starting with the letter 'm'. What convention is this, and where does it originate from?

It stands for member. I personally find this convention unhelpful, but it's subjective.

See Android Code Style Rules: Field Names. The use of the "m" prefix is more specific that simply denoting a "member" variable.

출처 - http://stackoverflow.com/questions/4237469/why-do-variable-names-often-start-with-the-letter-m