  The Standard Model of particle physics describes neutrinos as massless,
chargeless elementary particles that come in three different flavours. However,
recent experiments indicate that neutrinos not only have mass, but also have
multiple mass eigenstates that are not identical to the flavour states, thereby
indicating mixing. As an evidence of mixing, neutrinos have been observed to
change from one flavour to another during their propagation, a phenomenon
called neutrino oscillation.
  We have studied the reasons and derived the probabilities of neutrino flavour
change, both in vacuum and in matter. We have also studied the parameters
affecting this probability. We have discussed the special case of two-neutrino
oscillations. Lastly, we have discussed some basic properties of neutrinos that
are reflected in the previous derivations and highlighted a few relevant open
problems.
  To begin with, we have also studied the relevant topics in introductory High
Energy Physics and Quantum Mechanics to familiarize with the notations, units
and methodologies that would be required for the subsequent topics.
