The story is set in the future, approximately the year 2070. An alien race known as the Formics (often called the Buggers by children) has attacked Earth twice. Humans were very nearly destroyed the second time around, and would have been annihilated were it not for the work of Mazer Rackham. Now the government is preparing for the next invasion, gathering all of Earth's brightest children and sending them to Battle School, where they will learn to use their military genius to win the next Formic War.
The story centers around a child named Andrew Wiggin (given the nickname "Ender" by his sister's mispronunciation of his name). At the beginning of the book, Ender is only six. He is recruited into the IF (the International Fleet) and taken to Battle School, where he endures six years of intensive training. But Ender is not just another one of the children at Battle School; he is the one on whom all the government's hopes are pinned. For Ender is the best of the best, the genius among genius, and he is to be the next commander of the human fleet.
HERE.