'Seals' in the Bible

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

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

And one of the elders saith unto me, Weep not: behold, the Lion of the tribe of Juda, the Root of David, hath prevailed to open the book, and to loose the seven seals thereof.

And they sung a new song, saying, Thou art worthy to take the book, and to open the seals thereof: for thou wast slain, and hast redeemed us to God by thy blood out of every kindred, and tongue, and people, and nation;

And I saw when the Lamb opened one of the seals, and I heard, as it were the noise of thunder, one of the four beasts saying, Come and see.