Port wine is a type of wine made by adding a distilled liquor, prematurely stopped the fermentation process. Not only does this increase the alcohol content of the wine, but it leaves residuals sugars still resident in the wine. Thus port is sweeter and less "tart" or "acidic" than typical red wines.
Many people who do not like the "bite" of red wines, will love port, especially if they have a natural sweet tooth. It has a much more natural grape flavor, leaning toward a bit of cherry, wood, apricot, etc.
Wikipedia however launches into it's typical ridiculous nonsense by claiming that only those ports produced in a certain region of Portugal are true ports. Please. Is this the nineteenth century here?
Port is defined by the method of manufacture, not by the region where some old gnomes have clinched their teeth to prevent progress. I suppose "true" blue cheese can only come from one small town in France now?
What a bunch of lunacy.