Wind is the flow of air above the surface of the Earth in an approximate horizontal direction. Wind is named according to the direction it comes from, so a west wind blows from the west to the east.
Wind is caused by the uneven heating of Earth's surface by the sun. Differences in air pressure are created because different surfaces absorb solar heat in varying amounts. Hot air rises and creates an area of low pressure underneath it, while cool air falls and creates high pressure above it. Air from high pressure areas flows into nearby low pressure areas, creating wind.