He was a slow developer, supposedly not learning to speak until the age of three. He left Germany to avoid military service and attended the Swiss Federal Polytechnic School He studied physics and did not excel, only gaining a third class degree. He found it difficult to get a Job or academic position, and became a patent clerk in the Swiss patent office in 1902.
In 1905, he published four scientific papers during what became known as his 'Miracle Year'. One was to explain Brownian motion, one to explain the photoelectric effect and the third was to propose a 'special theory of relativity', as opposed to Galilean relativity. This third paper was revolutionary, overthrowing our idea of space and time for a new concept of 's[acetime'', in which space and time were part of a four dimensional space. The fourth was also revolutionary, proposing that matter was essential frozen energy, and that mass and energy were related via the equation
In 1905 Einstein published his General Theory of Relativity. This made Einstein world famous. The Special Theory assumed a space empty of matter. The General Theory allowed for matter, and predicted that spacetime was curved in the presence of matter. Many experiments have been done, all supporting the validity of the General Theory.
In 1921 Einstein won the Nobel prize for his work on the photoelectric effect.
When the Nazis came to power in 1933, Einstein living in Germany was on a speaking tour. He opted not to return and accepted a job at Princeton University in the USA. German newspapers printed the headline, 'Good News: Einstein is not Coming Back!'.
For the rest of his life Einstein devoted himself to looking for a 'Grand Unified Theory' to explain all of physics in a single framework, and to question the foundations of quantum physics.
He retired in 1945 and died in 1955, aged 75.