The detail mechanism is explained in the next section. The charges built up have to be earthed. The earth is considered to be a reservoir of electrons, so the electrons from the earth travel up, through your body. If the charges are not earthed soon, you may get a sharp shock if you touch anything metallic. The sharp shock is due to charges built up in your body being electrically neutralized by the electrons hopping from the metal you have touched.
Static electricity is observed only in insulators.
In conductors , the electrons move around freely. Most metals are conductors. In our electrical wiring the metal threads are either copper or aluminum. In metals, the electrons are bound to many atoms at the same time. This type of bonding is either ionic or metallic bonding.