Today, the Moon, second brightest object in the sky, has reached the New Moon phase, which means that it is directly between the Sun and Earth, and thus invisible for us Earthlings as of now.
As for lunar mechanics, the Moon is always half lit. The reason we don't always see it as such is thanks to orientation in relation to us. Right now, with the Moon directly between the Earth and Sun, e can't see any of its lit side.
After today, we will see more of the Moon each night as its lit side turns more toward from us and heads toward first quarter.