The lunar phase or phase of the moon is the shape of the illuminated (sunlit) portion of the Moon as seen by an observer on Earth. The lunar phases change cyclically as the Moon orbits the Earth, according to the changing positions of the Moon and Sun relative to the Earth. The Moon's rotation is tidally locked by the Earth's gravity, therefore the same lunar surface always faces Earth. This face is variously sunlit depending on the position of the Moon in its orbit. Therefore, the portion of this hemisphere that is visible to an observer on Earth can vary from about 100% (full moon) to 0% (new moon). The lunar terminator is the boundary between the illuminated and darkened hemispheres. Each of the four "intermediate" lunar phases (see below) is roughly seven days (~7.4 days) but this varies slightly due to the elliptical shape of the Moon's orbit. Aside from some craters near the lunar poles such as Shoemaker, all parts of the Moon see around 14.77 days of sunlight, followed by 14.77 days of "night". (The side of the Moon facing away from the Earth is sometimes called the "dark side", which is a misnomer. It receives just as much sunlight as the Earth-facing side − actually slightly more, since the Earth never obscures the Sun from it.)
I spent my life twenty years in the basin
My only friend was a man of much more
He lied with power in his weary eyes 'till day came
And all at once I knew his name
Giles of the river...comin' in to make my precious day
Giles of the river...comin' in to tell one tale and take
My breath away...and he's on his way
He took me down through good times late departed
And through the world as it was and will be
By bad self I watched you as you hung your head out my door
But you won't grieve me no more