Rumors of a relationship between Brad Pitt and Angelina Jolie started during the filming of the movie Mr. and Mrs. Smith, while Brad was still married to television star Jennifer Aniston. One month after Aniston filed for divorce, in April of 2005, a set of paparazzi photographs emerged that seemed to confirm that those rumors were true. According to Wikipedia, the photos sold for approximately $500,000, and showed Brad on the beach with Angelina and her adopted son Maddox.
In July of 2005, Brad accompanied Angelina to Ethiopia, where she adopted her second child, a girl named Zahara. Brad would later file to become the adopted-father of both of Angelina's children. On January 19 of 2006, a California judge approved his request, and both children's last names were formally made "Jolie-Pitt".
It was on January 11 of 2006 that Angelina Jolie first confirmed that she was pregnant with Brad Pitt's child. She gave birth to a daughter, whom the couple named Shiloh Nouvel Jolie-Pitt on May 27, 2006. The baby was born in Swakopmund, Namibia and was delivered via a caesarean section.
In March of 2007, Angelina adopted another child. This one was a boy from Vietnam named Pax Thien, now known as Pax Thien Jolie-Pitt. The orphanage that he was adopted from did not allow unmarried couples to adopt a child, so Angelina adopted Pax as a single mother. Brad later adopted him within the US.
In May of 2008, Angelina confirmed that the couple was expecting twins. On July 12, 2008 she gave birth to a boy named Knox Léon Jolie-Pitt, and a girl named Vivienne Marcheline Jolie-Pitt. Knox weighed 5.03 pounds, and Vivienne weighed 5 pounds. Both were delivered via caesarian section.