A solar eclipse is the result of the moon coming between the Earth and the sun. During an eclipse, the moon casts its shadow upon the Earth. A total solar eclipse can only occur during the phase of the new moon.
There are four types of solar eclipses: annual, partial, hybrid and total. Hybrid and total eclipses involve a complete occlusion of the sun's disk, while annual and partial eclipses do not fully block the sun. Partial eclipses do not fully block the sun's disk, although how much of the sun remains in view depends on the viewing location and circumstances. An annual solar eclipse requires the moon to pass centrally in front of the sun, but occurs when the moon is at too great a distance to occlude the sun completely.
A total eclipse occurs when the moon is able to occlude the sun completely and happens somewhere on Earth approximately every 18 months. A hybrid eclipse begins and ends just like an annual eclipse, although the curvature of the Earth results in a total occlusion of the sun at its peak. Some form of solar eclipse can be expected to occur between two and five times each year.