'Seals' in the Bible

And I saw on the right hand of him that sat upon the throne a book, written within and on the back, sealed with seven seals.

And I saw a strong angel proclaiming with a loud voice, Who is worthy to open the book, and to break its seals?

And one of the elders says to me, Do not weep. Behold, the lion which is of the tribe of Juda, the root of David, has overcome so as to open the book, and its seven seals.

And they sing a new song, saying, Thou art worthy to take the book, and to open its seals; because thou hast been slain, and hast redeemed to God, by thy blood, out of every tribe, and tongue, and people, and nation,

And I saw when the Lamb opened one of the seven seals, and I heard one of the four living creatures saying, as a voice of thunder, Come and see.