What makes Madeira, Marsala, Port, Sherry and other fortified wine unique? Think about (and answer) the questions that guide us in determining what makes a wine taste as it does:

Grape variety, climate, vinification practices, viticultural practices, location and the luck of the year. Compare what you find in your text book to what is conveyed about Madeira: http://winefolly.com/review/what-is-madeira-wine/, Marsala: http://winefolly.com/review/marsala-wine/ Porto: http://winefolly.com/review/what-is-port-wine/  and Sherry: http://winefolly.com/review/dry-sherry-wine-guide/