The way to identify which of the phases the moon is in is based on which section of the moon's face is lit by the sun. The moon has eight phases, which happen in the same cycle over the course of a 29-day period.
The phases of the moon are broken into four quarters. The first quarter is the new moon, which is followed by the first quarter, full moon and last quarter. During the new moon phase, the moon isn't visible because it is too close to the sun. This phase is the start of the lunar cycle. The next phase is known as the waxing crescent and it exposes between 1 and 49 percent of the moon. The phase that comes after is called the first quarter and it is when exactly half of the moon is visible. After this phase the waxing gibbous begins, which is when 51 to 99 percent of the moon is lit. The entire illumination of the moon's disc is known as the full moon. After these phases, the moon starts to move back into the new moon phase. During the waning gibbous, third quarter and waning crescent, the moon progressively gets lit less and less until it reaches the new moon phase again.