The oily skin type is generally characterised as shiny and sometimes greasy, with large visible pores. The increased activity of the sebaceous glands gives the skin a thicker texture. It is also more prone to blackheads and pimples.
The oil that you skin produces (or sebum as it's called) is not bad for your skin, on the contrary, it is necessary as it helps your skin retain moisture and protects your skin from the signs of ageing. Excessive sebum production can however be challenging, and visually unappealing.