'Altar' in the Bible

When the Lamb broke the fifth seal, I saw underneath the altar the souls of those who had been slain because of the word of God, and because of the testimony which they had maintained;

Another angel came and stood at the altar, holding a golden censer; and much incense was given to him, so that he might add it to the prayers of all the saints on the golden altar which was before the throne.

Then the angel took the censer and filled it with the fire of the altar, and threw it to the earth; and there followed peals of thunder and sounds and flashes of lightning and an earthquake.

Then the sixth angel sounded, and I heard a voice from the four horns of the golden altar which is before God,

Then there was given me a measuring rod like a staff; and someone said, “Get up and measure the temple of God and the altar, and those who worship in it.

Then another angel, the one who has power over fire, came out from the altar; and he called with a loud voice to him who had the sharp sickle, saying, “Put in your sharp sickle and gather the clusters from the vine of the earth, because her grapes are ripe.”

And I heard the altar saying, “Yes, O Lord God, the Almighty, true and righteous are Your judgments.”