The sun drives us and our weather via its numerous, complex and gorgeous activities. The work in this book deals with the effect of solar transients on earth i.e. in producing geomagnetic storms. It presents the interplanetary and terrestrial effects of few geo-effective Coronal Mass Ejections (CMEs) detected during maximum activity period of solar cycle 23. Another recently recognized and interesting aspect of solar-terrestrial physics called Solar Wind Disappearance has also been investigated. Multi-wavelength observations of Interplanetary Medium are also discussed. The effects of space weather on space technological systems have gained utmost concern, because of our increased space activities.