In this review, we discuss various cosmological issues related to our Unive
rse from a string theoretic perspective. We analyse the pre-big bang cosmol
ogical scenario which appears naturally in this context due to the existenc
e of scale factor duality symmetry in string theory. We then discuss some o
f the attractive and problematic features of this scenario. Finally, we int
roduce a method which is powerful enough to search for cosmological solutio
ns in various low energy limits of string theories.