What is a factory pattern? code example

Example: simple factory pattern

enum FanType
{
    TableFan,
    CeilingFan,
    ExhaustFan
}

interface IFan
{
    void SwitchOn();
    void SwitchOff();
}

class TableFan : IFan {.... }

class CeilingFan : IFan {.... }

class ExhaustFan : IFan {..... }

interface IFanFactory
{
    IFan CreateFan(FanType type);
}

class FanFactory : IFanFactory
{
    public IFan CreateFan(FanType type)
    {
        switch (type)
        {
            case FanType.TableFan:
                return new TableFan();
            case FanType.CeilingFan:
                return new CeilingFan();
            case FanType.ExhaustFan:
                return new ExhaustFan();
            default:
                return new TableFan();
        }
    }
}

//The client code is as follows:

static void Main(string[] args)
{
        IFanFactory simpleFactory = new FanFactory();
        // Creation of a Fan using Simple Factory
        IFan fan = simpleFactory.CreateFan(FanType.TableFan);
        // Use created object
        fan.SwitchOn();

        Console.ReadLine();
 }