no one may buy or sell
In order to enforce worship of the Beast and his image, the mark is tied to his global economic system. Those who refuse the mark are automatically cut off from the global economy. They are driven underground to rely either upon supernatural provision (as the woman in the wilderness of Revelation Rev. 12:6+) or the black market. Some manage to survive outside the global economy, including the sheep in the Sheep and Goat Judgment at the return of Christ to take up His kingdom(Mtt. Mat. 25:31-32). The sheep have provided for the dire needs of Jesus brethren during this time, but they themselves have been without the mark. For it is not possible to take the mark and remain among the redeemed who enter the kingdom (Rev. Rev. 14:9-11+).
There are several aspects of modern technology which will likely contribute to the control of the global economy under the Beast. First, the mark itself may be tied into a cashless system of exchange. While Scripture does not say this, how effective it would be to do away with all means of value exchange except for that which requires the mark. Second, the use of modern identifying marks, such as bar codes, on items of commerce facilitates tracking their whereabouts and distribution. With sophisticated inventory systems it becomes much more difficult to supply the black market off the record.
The degree to which technology plays in the system of the end is pure speculation. It may utilize systems of identification, tracking, and exchange yet unknown to us. Or it may use the oldest of technologiestattoos or similar. The desire of the Beast to catch every possible violator argues for a high-technology solution which is more difficult to forge. The disruptive conditions on the earth during the time of the end argue for a low-technology solution.
who has the mark or the name of the beast or the number of his name
The TR text indicates three alternatives: (1) the mark, or (2) the name of the beast, or (3) the number of his name. The MT and NU texts indicate just two alternatives: the mark which is: (1) the name of the beast, or (2) the number of his name. In any event, the mark embodies information pertaining to the name of the Beast.
the number of his name
Most commentators take the number of his name to indicate the practice of gematria, where the individual letters comprising the name are given values which then contribute to a total value which is the number:
The mystic use of numbers (the rabbinical Ghematria, γεωμετρία [geōmetria] ) was familiar to the Jews in Babylon, and passed from them to the Greeks in Asia. It occurs in the Cabbala, in the Sibylline Books (I. 324-331), in the Epistle of Barnabas, and was very common also among the Gnostic sects . . . It arose from the employment of the letters of the Hebrew and Greek alphabets for the designation of numbers. The Hebrew Aleph counts 1, Beth 2, etc., Yodh 10; but Kaph (the eleventh letter) counts 20, Resh (the twentieth letter) 200, etc. The Greek letters, with the addition of an acute accent (as ά, βˊ), have the same numerical value in their order down to Sigma, which counts 200; except that σ῀ (st, [stigma]) is used for 6, and φˊ (an antiquated letter Koppa between π and ρ) for 90. The Hebrew alphabet ends with Tav = 400, the Greek with Omega = 800. To express thousands an accent is put beneath the letter, as α, [a,] = 1,000; β, [b,] = 2,000; ι, [i,] = 10,000.1Again, there is evidence that the number is the same for all who receive it:
Doubtless, the invention of computers and the introduction of a cashless society would aid in the enforcement of an economic boycott against Christians. However, the mark is the name of the beast or the number of his name (Rev. Rev. 13:17+) not the name or number that identifies each individual citizen.2