In between the sixth and seventh seal being opened we see the living God marking those who serve Him. The seals on their foreheads were to be given before the four angels were given power to harm the land and the sea. The number of those who are marked, or sealed are 144,000. Numbers represent ideas in Revelation. Those who come out of the great tribulation, clothed in white robes that have been washed in the blood of the Lamb, are richly rewarded in the presence of God!