The Solar Wind is wind from the sun. It is a stream of charged protons and electrons and plasma shot out of the Sun. They are shot out at such speed that they can travel the whole length of the Solar System, nearly 1 light year. The particles are dangerous to people and spacecraft. A solar storm in 1989 brought down the Quebec electric power grid putting the entire province in darkness. If we were to have another solar storm as strong as the one in 1859 it is estimated it would cause up to 2 trillion dollars damage, Earth has a magnetic field which absorbs or soaks up a lot of the solar wind causing the Northern lights and Southern lights.
Solar wind also causes the tail of a comet. When the comet is close enough to the sun that the heat causes the ice of the comet to melt and evaporate, the motion of the solar wind causes the resulting water vapor to stream away from the comet. Because it is blown by the solar wind, the comet's tail does not trail behind it, but always points directly away from the sun.