What are the Differences Between a Scarf, Shawl, Wrap and Stole?

When people ask me about my online scarf boutique, www.elizabetta.net, they often ask me what are the differences between a scarf, shawl, wrap and stole.

A rectangular or oblong can usually be worn as a shawl or a long scarf

There seems to be a fair amount of confusion about these terms and [...]