Alfvén waves are a type of magnetohydrodynamic wave that occur in plasmas, which are ionized gases found in space. Named after physicist Hannes Alfvén, these waves propagate along magnetic field lines, allowing energy and information to travel through the plasma. They play a crucial role in various astrophysical phenomena, including solar flares and the behavior of the solar wind. These waves are characterized by oscillations of charged particles, such as electrons and ions, in response to magnetic forces. Alfvén waves can influence the dynamics of stellar atmospheres and contribute to the heating of coronal plasma in stars, making them important for understanding space weather and cosmic events.