Recent progress in ultrafast lasers has provided lot of opportunities in visualizing atomic and molecular dynamics at femtosecond (quadrillionth of a second) and attosecond (quintillionth of a second) time scales. This advancement gave birth to a Nobel winning broad field of inter-disciplinary science known as â€œUltrafast Scienceâ€. In this presentation, I will discuss about state-of-the-art developments in femtosecond extreme-ultraviolet light sources generated through high harmonic generation. The light sources in combination with molecular fragmentation imaging techniques (e.g. COLTRIMS) enable us to understand photo-induced molecular dynamics in gas-phase molecules profoundly. I will also be discussing a series of experimental results of ultrafast molecular dynamics studied using ultraviolet or extreme-ultraviolet-pump and near-infrared probe pulses in CO2 and O2.