Today many people put petrol into their motor cars and heat their homes and cook their food by gas, but for most of their other energy needs, at home, at work, at school, for recreation, they use electricity.
Since 2008 more that half of all the people in the whole world live in small houses in large towns. Most of these people cannot (at present) generate all the electricity they need in their own homes, they must use mains electricity for at least some of the time. This Page is about mains electricity.
Although more than half of all people live in large towns this is not everyone: in some European countries there are still whole villages where there is no mains electricity, in some continents there are still whole countries where there is no mains electricity outside the largest towns. Life “Off The Grid” is discussed later.
In most of the world mains electricity in most homes is usually
Each of these is discussed separately below. In the United States and Canada most homes have a 240 V supply, but inside the home some appliances use 240 V and some 120 V - this is described later.
The technology, and the price of this technology, is changing very rapidly at the moment, and there will be many changes in the way we produce, distribute and use electricity over the next few years, and some of these are discussed below. But it is unlikely that the need for mains electricity, or the way in which it is supplied into our homes, will change.
After the Second World War many countries tried to agree to standardise mains voltage and frequency, but today small solid state adapters using modern semi-conductor technology which convert between all the different voltages and frequencies (and sockets!) are widely available so the differences between countries is not the problem that it once was. Just make certain you take the right adapter with you when you go on holiday! Search on the Web to find out which one you need for where you are going. A lot of equipment, particularly chargers for mobile phones, will work with any voltage and any frequency, and will be labelled to this effect (but you still need the right plug on the end).
Each Page that follows builds on the ones before it but you can also go straight to any Page. The scarab
takes you on to the next Page, the owl 
takes you back to this Index, or from this Page to the Index to my Science Pages, and the Eye of Horus takes you back to the Main Index to my Web Site. 
Why alternating current?