All static electricity effects come from electrons moving. Walking across a nylon carpet, you rub against the carpet and electrons are transferred, so your body builds up charge. When you then touch a metal door handle, electrons flow between you and the handle. Metal is a good conductor, so the charge moves quickly and you feel a small shock, sometimes with a spark.
Lightning is the same process on a huge scale. In a storm cloud, ice crystals and water droplets rub against each other and electrons are transferred, so parts of the cloud become strongly charged. The charge builds up until the air, which normally acts as an insulator, can no longer hold it back. Electrons then flow through the air to the ground as a giant spark.
A charged object can also attract a neutral one by induction. A balloon rubbed on hair gains electrons and is negative. Held near a wall, it pushes electrons in the wall surface away, so the surface nearest the balloon becomes slightly positively charged. The nearer positive charge attracts the balloon more strongly than the further negative charge repels it, so the balloon sticks. A charged comb picks up small pieces of paper in the same way.
