The Infosphere was a massive biological memory bank created by the Brain Spawn in an effort to catalog all information in the universe.
The Brainspawn have been collecting information in the universe for a thousand years, planning on attaining everything and then destroying the universe so no new info can be made. When the information collecting was complete, the Infosphere opened to scan itself.
The Nibblonians dispatched Philip J. Fry to plant a quantum interface bomb so they could send the Infosphere and the Brainspawn into another universe forever. However, Fry took the opportunity to ask the Infosphere about the greatest questions he wants to know, like "is postage glue made from toad mucus?". Unfortunately, this alerted the Brainspawn to his presence and his Scooty-Puff, Jr. came apart. In one last heroic stand, Fry activated the bomb, claiming he would lead good to victory over evil. However, the Brainspawn persuade Fry to ask the Infosphere what really happened the night Fry was frozen. It was revealed to be Nibbler who pushed him into the cryogenic tube. Feeling hurt that the Nibblonians betrayed him, Fry gets sucked into the other universe with the Brainspawn.
When Fry lamented that he wished Nibbler hadn't froze him, the Infosphere revealed that it was possible for Fry to go back in time and stop Nibbler from tripping Fry.