Kaf is a dark and bitter drink brewed from beans and is popular (and exclusive) among the Seanchan. Kaf is served in small cups that drinkers balance on their finger tips and is used both as a daily indulgence and as a welcoming gesture with a friend or ally. Westlanders who drink kaf tend to think of it as undrinkable and that no amount of honey could possibly salvage the taste. Seanchan, on the other hand, find tea to be an extremely weak and unflavorful beverage by comparison. Kaf is a beverage to be savored, the "aroma of kaf is almost as enjoyable as the flavor."
Kaf is analogous to coffee (Which can also be assumed by its name - Kaf sounds similar to Kafe, the arabic & hebrew word for Coffee), or possibly espresso. It is served in small cups that resemble demitasse cups, but without handles.