Albert Einstein became interested in physics at the age of 5, when his father gave him a compass. This fascination was matched by his enthusiasm for music, especially violin playing. But his teachers thought he had limited scholastic ability. He left school at 15 with no diploma, only a letter of recommendation from his mathematics teacher.
In the year after leaving school, Einstein spent a lot of time performing thought experiments. For instance, he gazed into a mirror and wondered what would happen to his reflection if he were moving at the speed of light. This thought experiment is now known as Albert Einstein's mirror. He concluded that light moves at the same velocity, independent of any observer. Initially, he kept this view to himself. But he decided to pursue a career in physics, so he could play with these kinds of ideas.
He took the entrance exam to the Federal Polytechnic Academy in Zurich, Switzerland, two years early at age 16—and failed. But his outstanding marks in mathematics and science got him in. In his subsequent four year course in physics and mathematics he learned much, but did not get on with his lecturers. He probably learned more from discussions with friends in the local coffee houses. He avoided the taverns, believing that "beer makes a man stupid and lazy."
In 1901 Einstein went through a succession of short-term teaching posts, but could not fulfil his desire of finding an academic post at a University. Also, his girlfriend, Mileva Maric, became pregnant. He applied to work as a patent officer in Berne, Switzerland, a post he would hold for seven years. During this time he developed the profound ideas that appeared in three published papers in his "miracle year", 1905. These were on special relativity, the photoelectric effect, and Brownian motion.
In 1908 an academic post at Berne University was given to him. By 1915 he had completed his general theory of relativity was, and in 1917 his cosmological model followed. In 1919 an expedition led by Sir Arthur Eddington photographed stars near to a solar eclipse and showed that the observed deviation of the stars from their expected position, due to their light rays being bent by solar gravitation, was predicted by general relativity.
Einstein's great successes in relativity were not the reason for him being given the 1921 Nobel Prize for Physics. This was won for work his on the photoelectric effect, which, at this time, had more experimental verification.
In 1927 Einstein Attacked the Copenhagen interpretation of Quantum mechanics and the non-determinism introduced by Heisenberg's uncertainty principle. He said, “God does not play dice.” Bohr countered with, “It is not our business to describe to God how he should run the world.” He began concentrating on his embryonic unified field theory, but this work would remain unfruitful throughout his career.
Einstein supported his own model of a static universe until 1931, when he finally accepted the Big Bang model. In 1932 he left Germany and by 1934 was firmly ensconced in Princeton's Institute of Advanced Study, where he published a seminal paper on the Einstein-Podolsky-Rosen paradox.
In 1952 Einstein was offered the presidency of Israel but declined. His last letter, in 1955, was to Bertrand Russell and supported nuclear disarmament.
Further reading: The short biography of Albert Einstein in Encyclopedia Britannica has more detail, and is linked to original articles by Einstein himself.