'Sign' in the Bible

John came, and gave baptism in the waste land, preaching baptism as a sign of forgiveness of sin for those whose hearts were changed.

And the Pharisees came forth, and began to question with him, seeking of him a sign from heaven, tempting him.

And he sighed deeply in his spirit, and saith, Why doth this generation seek after a sign? verily I say unto you, There shall no sign be given unto this generation.

Tell us, when shall these things be? and what shall be the sign when all these things shall be fulfilled?

But take care: for they will give you up to the Sanhedrins; and in Synagogues you will be whipped; and you will be taken before rulers and kings because of me, for a sign to them.

Now he that delivered him up had given them a sign between them, saying, Whomsoever I shall kiss, that is he; seize him, and lead him away safely.