How Old Is The World?

Scientists estimate that the world is probably in the region of 4,500, 000, 000 years old.  That is 4.5 billion years.
Most of these believe that the world was formed when the solar system developed.  The solar system emerged when a huge cloud of gas and dust swirled endlessly around the sun.  As the cloud whirled, it slowly began to flatten out and sections of it began to spin like whirlpools in a stream.  Gas and dust combined to collect near the centre of these whirpools.  Over a period of time the gas and dust formed into balls which grew ever larger and eventually developed into the Earth and the other planets contained within the solar system which now circle the sun.  
All this happened over a period of billions of years.  The world did not 'appear' as a result of a Big Bang which suddenly produced a solar system, but the Big Bang formed the foundations for the world to develop.

About 4.6 billion years old.