Porter

Porters are very dark in colour, a dark red brown to black and should be clear when you can see through them at all.
They usually have a thick off white head and a fairly thin but not watery mouthfeel.
Tastes are toasty with flavours of chocolate, coffee and often caramel. Other flavours can include raisin or berry, nuttiness, molasses or licorice.
Porters are often flavoured with extra coffee or chocolate, and sometimes berries.
They vary from stouts in that stouts are usually stronger in both flavours and alcohol content, and stouts use roasted barley whereas Porters use dark malt.
The bitterness in a Porter is usually relatively mild allowing the malt tastes to predominate.
Alcohol content is usually between 4% to 6.5% ABV.