Phosphorus is a nonmetallic element that exists in several allotropic forms. White phosphorus is a soft, waxy, flammable substance consisting of tetrahedral P4 molecules; this allotrope spontaneously ignites in air at about 30°C, and is usually stored under water. Red phosphorus is a red, powdery material which consists of cross-linked molecules of phosphorus; this allotrope is stable at room temperature, but can be converted to flammable white phosphorus by friction, heat, or sunlight. For more information about phosphorus, click here.
This is a sample of white phosphorus, which is somewhat old, and no longer very pure. There are some yellow discolorations which are typical of white phosphorus which has been sitting around for some time. The chunks are usually stored under water to prevent them from igniting, but I removed them from the water temporarily to take these pictures. (You can see some slight wisps of smoke in some of the pictures, especially the last one.)
The following pictures show a chunk of phosphorus which has been lit with a match. For a video of burning phosphorus, click here.
The following pictures show some strike-anywhere matches and safety matches. The tip of the strike-anywhere match contains phosphorus sesquisulfide, P4S3, a nontoxic, stable compound, which is converted to flammable white phosphorus when the match-head is dragged across a rough surface. (The match-head usually also contains powdered glass to increase the friction.) Once the white phosphorus ignites, it causes potassium chlorate, KClO3, in the match-head to burn, producing molecular oxygen, which further feeds the combustion reaction, until the wooden stick starts to burn. In safety matches, the phosphorus is not in the match-head, but is instead on the side of the box, thus separating the components that are necessary to ignite the match. Dragging the match-head across the rough surface of the box converts some of the red phosphorus into white phosphorus, which ignites the match-head, once again causing potassium chlorate to produce molecular oxygen. (If you drag a match-head across the phosphorus on the match box slowly, you can see little sparks that are produced with red phosphorus is converted to white phosphorus, but I don't have a camera which is sensitive enough to record them here.)