Graphite is a good conductor of electricity because its electrons are delocalized or free to move around. Graphite is structured into planes with tightly bound atoms. There is a great deal of distance between planes, and they are bonded weakly together, allowing the electrons to move around.
Because graphite is such a great conductor, it is used in electrical cells. It is also found in motor oil and pencils. Because graphite is soft, it is combined with clay, and baked, and hardened before being inserted into wood for pencils.
Graphite is made up of bonded carbon atoms. One carbon atom is strongly bonded to three other carbon atoms, resulting in carbon sheets. Each carbon atom is then bound weakly to two other carbon atoms, one to the sheet above it and another to the sheet below it. The strong bonds give graphite high boiling and melting points, while the weak bonds make graphite soft and flexible.
Graphite is closely related to diamonds. Both have crystalline forms. However, diamonds are one of the hardest materials known to man, while graphite is not. There is a process that turns graphite into industrial-grade diamonds - a metal catalyst and graphite are heated and pressurized together.