With the advent of radio telescopes such as LOFAR, MWA, PAPER, 
a new observational window on the high-redshift universe has 
been opened. More specifically, we expect in the near future 
to be able to detect for the first time the 21cm signal from 
the diffuse Intergalactic Medium (IGM) prior to its full 
reionization and thus probe the "dark ages". In this talk 
I will discuss about the theoretical modeling of the 
reionization process, the observability of the associated 21cm 
signal and the efforts ongoing within the LOFAR Epoch of 
Reionization Working Group.