Graphene is a two-dimensional indefinitely extending sheet of covalently bonded carbon atoms, which form a structure similar to that of a tessellation of hexagons. Graphite, found in pencil leads, consists of innumerable layers of graphene stacked on top of each other.
Its isolation was deceptively simple; after many years of trying to grow single layers of graphene on a matrix, some researchers simply took some tape, sticked it on some graphite, and peeled the tape off. A single layer was produced!
Graphene is aromatic; each carbon has 3 bonds, and one single pi-electron from each atom is delocalised across the entire plane. Consequently, graphene conducts electricity across its plane; for this reason, graphite also does so in the direction parallel to the graphene sheets that constitute it.
This is why graphene is seen to have great promise in technology; it is both transparent and flexible, and can also conduct electricity. As a result, it has been proposed to be used in various applications, such as solar panels and touchscreens.
It also has exceptional tensile strength; compared to steel of equal thickness, it is 100-200 times stronger. This has led it to be considered as a structural material; tennis rackets and cars made from graphene have been produced.