2012 is leap year, what is a leap second ?

1) LEAP SECOND When mankind came to know that  the sun rises at different  times in different countries,  efforts were taken to fix  the country  that watches  first the rising of the sun .   Japan was identified . It is the country of rising sun. If  in Japan the time is   6 am, in  India it  is 2:30 am  ( 3:30; hrs less  from Japan time  )  It is the earth's rotation that  causes the time difference.   The sun is in different points in the sky  because of the rotation  of the earth. The time changes from country to country. The Earth rotates once in 24 hours,  it is not exactly 24 hours,  slightly less  in fraction of seconds .  As a result, once in a few years,  the rotation of the earth becomes  one sec less than the clock time, which needs adjustment. How is  this adjustment is done ? I will explain with a simple example.  A and B are two clocks running accurately ,  showing the  same clock time. At one stage,  A is running one sec more  than B. To make the two clocks  to show the same  time , Clock 'A' which is running forward  by  1 sec ,  should be stopped for one sec. Then A and  B will show the same clock time.  So, for the adjustment,  the object running forward should be stopped. Clock time is one sec forward than rotation time of the earth.. So, the  clock time  should be stopped for one sec.  It is done on 31st Dec midnight,   just before the birth of New Year. Universal clock and all other clocks including  the Big Ben of UK are stopped for one sec. It is called ' inserting  a leap second '. By this process, the rotation time and  the clock time are synchronized It is not  done  every year, done only when required . The last inserting of the  leap second was done in the year 2008, Dec 31st midnight.  ( some times done at the end of June also )