  Coronal Mass Ejections (CMEs), as they can inject a large amounts of mass and
magnetic flux into the interplanetary space, are the primary source of space
weather phenomena on the Earth. The present review first briefly introduces the
solar surface signatures of the origins of CMEs and then focuses on the
attempts to understand the kinematic evolution of CMEs from the Sun to the
Earth. CMEs have been observed in the solar corona in white-light from a series
of space missions over the last five decades. In particular, LASCO/SOHO has
provided almost continuous coverage of CMEs for more than two solar cycles
until today. However, the observations from LASCO suffered from projection
effects and limited field of view (within 30 Rs from the Sun). The launch in
2006 of the twin STEREO spacecraft made possible multiple viewpoints imaging
observations, which enabled us to assess the projection effects on CMEs.
Moreover, heliospheric imagers (HIs) onboard STEREO continuously observed the
large and unexplored distance gap between the Sun and Earth. Finally, the
Earth-directed CMEs that before have been routinely identified only near the
Earth at 1 AU in in situ observations from ACE and WIND, could also be
identified at longitudes away from the Sun-Earth line using the in situ
instruments onboard STEREO. Our review presents the frequently used methods for
estimation of the kinematics of CMEs and their arrival time at 1 AU using
primarily SOHO and STEREO observations. We emphasize the need of deriving the
three-dimensional (3D) properties of Earth-directed CMEs from the locations
away from the Sun-Earth line. The results improving the CME arrival time
prediction at Earth and the open issues holding back progress are also
discussed. Finally, we summarize the importance of heliospheric imaging and
discuss the path forward to achieve improved space weather forecasting.
