The mark of the Beast is associated with the number of the Beast, 666, and the name of the Beast in Revelation 13:17 Revelation 13:17And that no man might buy or sell, save he that had the mark, or the name of the beast, or the number of his name.
American King James Version×.
The following is an excerpt from the United Church of God booklet The Book of Revelation Unveiled:
"The second beast of Revelation 13 will cause 'all, both small and great, rich and poor, free and slave, to receive a mark on their right hand or on their foreheads, and that no one may buy or sell except one who has the mark or the name of the beast, or the number of his name' (Revelation 13:16-17 Revelation 13:16-17  And he causes all, both small and great, rich and poor, free and bond, to receive a mark in their right hand, or in their foreheads:
 And that no man might buy or sell, save he that had the mark, or the name of the beast, or the number of his name.
American King James Version×).
"What's behind this strange-sounding practice? How will it affect people as the time of the end draws near?
"There is historical evidence that, in the ancient Babylonian culture, slaves 'were identified…[by] some kind of mark, either tattooed or branded on the face or the back of the hand' (H.W.H. Saggs, The Greatness That Was Babylon, 1962, p. 173). There may be parallels between this ancient practice and what God reveals will happen in the end time.
"Many have speculated as to the meaning of this puzzling prophecy. Some interpret it in terms of supercomputers, unique personal identity numbers and even microchips imbedded under the skin.
"However, we should consider that receiving a mark on the hand or forehead could well be figurative. Remember from Revelation 7:3 Revelation 7:3Saying, Hurt not the earth, neither the sea, nor the trees, till we have sealed the servants of our God in their foreheads.
American King James Version×that God's servants were sealed on their foreheads. And in Deuteronomy 6 Moses told God's people to 'keep all His statutes and His commandments,' noting, 'You shall bind them as a sign on your hand, and they shall be as frontlets between your eyes' (Deuteronomy 6:2 Deuteronomy 6:2That you might fear the LORD your God, to keep all his statutes and his commandments, which I command you, you, and your son, and your son's son, all the days of your life; and that your days may be prolonged.
American King James Version×; Deuteronomy 6:8 Deuteronomy 6:8And you shall bind them for a sign on your hand, and they shall be as frontlets between your eyes.
American King James Version×). The hand and forehead here represent one's actions and thoughts respectively—which should be dedicated to obeying God.
"Likewise the mark of the Beast is evidently a mark of disobedience to God. Many Bible students have pointed to God's seventh-day Sabbath as an identifying sign of His people in Exodus 31:12-17 Exodus 31:12-17  And the LORD spoke to Moses, saying,
 Speak you also to the children of Israel, saying, Truly my sabbaths you shall keep: for it is a sign between me and you throughout your generations; that you may know that I am the LORD that does sanctify you.
 You shall keep the sabbath therefore; for it is holy to you: every one that defiles it shall surely be put to death: for whoever does any work therein, that soul shall be cut off from among his people.
 Six days may work be done; but in the seventh is the sabbath of rest, holy to the LORD: whoever does any work in the sabbath day, he shall surely be put to death.
 Why the children of Israel shall keep the sabbath, to observe the sabbath throughout their generations, for a perpetual covenant.
 It is a sign between me and the children of Israel for ever: for in six days the LORD made heaven and earth, and on the seventh day he rested, and was refreshed.
American King James Version×and see the mark of the Beast as running counter to it. They believe that forced observance of Sunday—a day originally dedicated to the worship of the sun as a god instead of the observance of the seventh-day Sabbath—could be involved. This view is strengthened by the fact that other prophecies in the book of Revelation show a great counterfeit religious figure and system will play major roles in leading people away from the true God and play into Satan's hands at this time.
"The Bible does not explicitly define the specific methods that the Beast will use to identify those free to participate in commerce at the time of the end. Some sort of advanced surveillance may be involved…
"However this prophecy is fulfilled, it is clear that it will involve compromising and contradicting God's commands. Having proof that one is officially associated in some way with the Beast will be necessary for one to be allowed to engage in the commerce."