The past few months have seen a resurgence of interest in open string field theory, triggered by Sen's ideas about tachyon condensation. Open string field theory allows a quantitative study of open tachyons off-shell processes. The main new surprise is that string field theory captures non-perturbative string dynamics, like D-brane physics. I will review recent work in the subject focusing on a proposal to formulate cubic open string field theory directly around the stable vacuum of the tachyon field. The ultimate question that this program wants to address is: can we give a full non-perturbative definition of string theory using only open string variables?