'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 back, close sealed with seven seals.

And I saw a strong angel proclaiming with a great 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 that is of the tribe of Judah, the Root of David, hath overcome to open the book and the seven seals thereof.

And they sing a new song, saying, Worthy art thou to take the book, and to open the seals thereof: for thou was slain, and didst purchase unto God with thy blood men 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 with a voice of thunder, Come.