What is the third apparition in macbeth?

The third apparition in William Shakespeare's play "Macbeth" appears as a child crowned with a tree in his hand. It delivers a cryptic message to Macbeth, warning him to beware Macduff. The apparition also tells Macbeth that he will not be defeated until Birnam Wood moves to Dunsinane Hill.

This apparition further fuels Macbeth's paranoia and fear of those who may be conspiring against him. It foreshadows Macbeth's eventual downfall as Birnam Wood does come to Dunsinane — in a symbolic way — when Malcolm's army camouflage themselves with branches from the forest.

Overall, the third apparition in "Macbeth" serves to further drive the plot and highlight the theme of deception and betrayal.