In this stage of the moon cycle, the moon is more than half way lit up, but it is not yet full.
It always appears high in the east, between noon and sunset, and sets a few hours after midnight.
This phase will come about one or two weeks after a full moon. It is now relatively far away from the sun in its orbit, so isn't hidden by the suns glare.
It is quite easy to see in the sky in the day time because quite a lot of the moons day side is facing earth. Therefore it is easier to see than a crescent moon for example, because more of it is lit up.
The term 'gibbous' derives from the meaning 'hump-backed', which can be seen in the lighted side of the moon. Any moon that is more than half lit up but not yet full is known as a gibbous moon.