What is halal meat? Is the sheep or goat slaughtered by Christians lawful to eat?

It is permissible to eat from animals slaughtered by a Christian or a Jew because of the general implication of the words of God Almighty Who says: "The food of the People of the Book is lawful unto you and yours is lawful unto them" (Quran 5: 5).
Meat is unlawful when:
- One is certain it comes from animals that are unlawful to eat.
- It comes from animals which have not been ritually slaughtered.
- It comes from animals slaughtered by a person who is not from among the People of the Book.
And God the Almighty knows best.