As the moon moves around Earth, that light strikes the moon from varying directions, which causes the moon to seem to shrink and fatten in phases that last for about a month. Most of us would like the moon to be around for a little while and then go away. Early this week, we can experience the moon at its best and then watch it set mercifully below the horizon, leaving us with blessed darkness to observe the rest of the universe. If it's cloudy this week, take heart. The same set of phases will repeat themselves every lunar month for all the rest of your days.
Most calendars mark the lunar phases.
Tonight is new moon, which means no moon at all, practically speaking. The moon's orbit has brought it almost directly between Earth and sun. We won't' see the moon tonight because it is too close to the sun to see. It would be nicely visible during the daytime if you didn't have to look nearly directly toward the sun to see it. Also, all the sunlight is thus shining on the part of the moon facing away from Earth.