Combination skin is one of the most common skin types.  It is characterized as having varying oil levels throughout the face.  The most oil build up is usually in the T-Zone (forehead and nose), while the rest of the face tends to have drier skin.  These areas are generally oilier than other regions of the face because they have higher percentage of oil glands.  Make sure when selecting facial products that they cater to combination skin otherwise you may do more harm than good.