What is a Member Variable in Android?

First If you need to Clear ourself What is a Class Variable or Static Variable and Instance variable.Read the below link for explanation

Static-variable-vs-instance-variable-in Android

Now What is a member Variable?

Member Variable is not a type of variable, Its a naming convention used in a class.

if the variable defined is a member of a class, we define its as member variable, Its done by prefixing the variable name with "m". There is nothing wrong if we don't follow, but android guidelines insist following this methodology for identification.