The most simple way of producing static ekectricity is by rubbing or friction. When you rub two different kind of materials that are insulator, you can transfer electrons from one substance to another. Nowadays, to create electricity we use battery and generators. Voltage can be made by heart, light or mechanical pressure. http://science.howstuffworks.com/electricity-info2.htm
2. Where and how is electricity used?
Electricity gives us ability to produce heat, which is essential in our life. Electricity makes heat and used in toasters, soldering irons and almost every machine. A very useful property of electricity is that it is a source of a magnetism. Electrons flow through wires which is how telephones, loudspeakers could work. Without electricity, we will be living in a place where there is no light at night. For a power source to work we need 'energy', just like the human body needs energy to function http://science.howstuffworks.com/electricity-info3.htm
3. How was it discovered?
Electricity was first discovered by a greek philosopheres. They discovered when amber was rubbed against the cloth, light weight objects stuck to it. Moreover, Benjamin Franklin flew his kite during a thunderstorm and when lightning flashed, the spark transferred from the key to his wrist. He could had easily been killed from electric shock. Without these people, the discovery of light bulb would have been impossible. http://www.gavinelectrical.com/content/history.htm
4. What is electricity how does electricity flow?
Electricity is a flow of tiny particles called electrons which can travel through wires. “Electron current” the name of this flow. Just like water, which can only flow down a hill, an electric current can only flow if there's something pushing the electron.