The Moon orbits the Earth close to the same plane as the planets.  This plane is called the ecliptic.  Since the Moon follows this path, it creates two kinds of eclipses, lunar and solar.

     Lunar eclipses occur when the Moon is full.  The Earth is between the Moon and the Sun.  There are usually two lunar eclipses a year.  

     Solar eclipses occur with the new Moon.  The Moon is between the Earth and the Sun.  There are usually two to five solar eclipses a year.  

     The Moon and the Sun return to nearly the same positions every 6585.32 days (about 18 years).  This period was know as the Saros to ancient astronomers.