Malbec is a red grape that probably originated around Bordeaux and is still a minor variety there. In France it is a major player in Cahors in the south-west of France but it is in Argentina that it found its most popular home.
Malbec makes deeply colored wines with fairly high levels of tannin which in good examples is matched by darker fruit flavors such as plum and blackberry. Woodsy and cedar notes can also be tasted in some Malbec. Aromas can be a bit subdued compared to the flavors.
Argentine Malbec are most often found as single variety wines but there are some nice examples that are blended with Cabernet Sauvignon, Cabernet Franc, or Syrah.
I have rarely tasted a bad Argentine Malbec and the can often be good values as nice ones can be had for under $15. Stepping up to just over $20 can yield some very nice wines. French Cahors are frequently overly tannic. Chasing after the international market that knows Malbec from Argentina has caused some makers of Cahors to make poorly balanced fruit bombs. There are some good Cahors but they tend to need at least five years of age before they reach a nice drinkable balance.