What is the exact difference between public and private inheritance?

what is the result of

class aClass : aBaseClass
{

};

is it public, private?

addititionally,

what are the conventions for implementing and interface and also deriving from some other base class?

example

class aClass: public aBaseClass, public IaInterface
{

};

or would you derive the IaInterface from the base class and use single inheritance?

Thanks