Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) are our neighbouring galaxies and prime locations for studying star formation, structure formation, interstellar medium, etc. The knowledge of reddening or extinction is very important in understanding structure and star formation in the galaxies. Recently, fourth phase of Optical Gravitational Lensing Experiment (OGLE) published large amount of data on variable stars in these two galaxies. In OGLE-IV database, there are 2476 fundamental mode (FO) and 1775 first overtone mode (FO) Classical Cepheids (CCs) in the LMC and 2753 FU and 1793 FO CCs in the SMC. In this talk, I will discuss about estimating reddening in LMC and SMC using CCs. By comparing the observed P-L relations with those of the extinction calibrated P-L relations, we estimated reddening E(V-I) across different regions of LMC and SMC. A comparison is also carried out with previous studies and with reddening obtained using different P-L relations. Employing these reddening estimates, a reddening map is also drawn for LMC and SMC. Reddening map of both galaxies shows irregular reddening distribution. The location of high reddening regions can be associated with presence of high dust and gas in those regions and star forming regions. We also derive the age of these Cepheids using Period-Age relation and discuss the spatial, age and spatio-temporal distributions of CCs in these two dwarf galaxies and their interpretation in understanding the star formation history in the Magellanic Clouds.