In this talk I will give an overview of our current knowledge about
the era of the formation of the first stars and galaxies in the Universe,
which ended with the complete reionization of the Universe.
According to our current understanding the very first stars formed
in a neutral and cold Universe some 50 million years after the Big Bang. By the
time the reached an age of 1 billion years radiation produced by stars,
supernovae and accreting objects had completely ionized and heated the Universe.
I will go through the basic theory and the constraints provided by current
measurements. I will also describe what can be expected from future measurements,
specifically measurements of the 21cm signal from neutral hydrogen with LOFAR
and the SKA.