An eclipse takes place when a body discontinues the light from a light source so that we can no longer see it shining. An eclipse can be either due to a dark body coming between us & a light emitter, so that we can no longer see the cause, or it can be a body approaching between a light source & the body that the light is enlightening, so that we no longer see the lighting body.
An eclipse of the Sun takes place when the Moon comes unswervingly between the Sun & the Earth so that the Earth lies in the silhouette of the Moon. An eclipse of Moon takes place when the Earth lies directly between the Sun & Moon and the Moon lies in the shadow of the Earth. If the orbit of Moon about the Earth rests in the same plane as orbit of the Earth about the Sun then there would be eclipses of the Sun & the Moon at every New & Full Moon respectively.
The amount of Moon's disk that is hidden depends on how close the Moon is to the nodule of its orbit at the phase of Full Moon. Like all shadows of light from a comprehensive source the shadow created by the Earth has umbra, where all light from the Sun is shadowed & a penumbra, where only some of it is. Penumbral eclipses of Moon take place when the Moon passes only through the penumbral shadow of the earth. Though these are catalogued they are subtle events and are not significant.
When the Moon passes through Earth's umbral shadow we can either see Partial Eclipse, when only fraction of the Moon is hidden, or Total Eclipse. Earth's shadow is much greater than Moon. During Total Eclipse, Moon doesn’t fade away completely but turns dark red. The colour and brightness depend on the state of Earth's atmosphere for Moon, during eclipse, is illuminated by light that has passed in the course of Earth's atmosphere & has been bent towards Moon by refraction.
Solar eclipse occurs when the Moon passes between Earth & Sun, thus partially or totally obscuring the Earth’s sight of the Sun. This pattern can only take place during new moon, when the Sun & Moon are in juxtaposition as seen from Earth. In olden times, & in some cultures today, solar eclipses are accredited mythical properties, thus swaying human civilization. Total solar eclipses can be startling events for people unacquainted of their astronomical nature, as the Sun abruptly disappears in middle of the day & sky darkens in minutes. Yet, the spiritual provenance of solar eclipses is now largely overlooked.
The eclipse of an actually small object by one which seems much larger is usually called an occultation. Observation of occultations by Moon were used for long time to get the most precise positions for the Moon and have been used to resolve the position & size of such strange objects as radio stars.