In the end times, what is the period known as the great tribulation?

from the old testament

• In between the rapture of the church and the millennial kingdom is the seven-year period during which the Antichrist comes to rule by the power of Satan. In Daniel 9:24–27, Daniel received a prophecy regarding the future of Israel. Seventy weeks—groups of seven years, or a total of 490 years—were to pass, after which sin would end, iniquity would be atoned for, everlasting righteousness would be instated, and the holy place anointed.
• The beginning of the seventy weeks would be the issuing of the decree to restore Jerusalem, which happened in c. 445 BC by King Artaxerxes of Persia (see Nehemiah 2:1–8). After sixty-nine weeks, the Messiah would arrive and then be cut off—marked by the triumphal entry of Christ and then His crucifixion.
• The final week of years is the tribulation. What we've come to understand that Daniel didn't know is that the church age was not included in those seventy weeks. The seventy weeks were the time designated for God to work through the nation of Israel. Between the sixty-ninth and the seventieth week have now been almost 2,000 years of God working through the church. But the final week will occur, and we know it as the tribulation, which is described in Daniel 9:26–27.
• In the beginning of the tribulation, the Antichrist will make a seven-year peace treaty with Israel and her enemies (Daniel 9:26–27), but later, he will reveal his desire to be worshiped and blaspheme against God and His people.
• After the Antichrist seemingly recovers from a fatal wound at the midpoint of the tribulation, Daniel says the Antichrist will put a stop to the sacrifices and the grain offerings (Daniel 9:27).
• Israel will suffer greatly after this midpoint period. Israel's distress will be greater than any Israel has experienced before (see Daniel 12:1; Jeremiah 30:7).

from the new testament

• In the seven-year tribulation period, Jesus identified the last half as the "great tribulation." It will begin with the revealing of the Antichrist (Matthew 24:21). It will last for forty-two months (Revelation 13:5), or three-and-a-half years. And it will end with the second coming of Christ (Matthew 24:29–30).
• Although the Antichrist will make a seven-year peace treaty with Israel and her enemies, at the midpoint, when the Antichrist apparently recovers from a fatal wound, he will blaspheme God and the temple, persecute the saints, and rule the world (Revelation 13:1–10).
• The Antichrist seemingly recovers from a fatal wound at the midpoint of the tribulation, and after this, Revelation says that believers will be imprisoned and martyred (Revelation 13:10; Revelation 20:4).
• While the Antichrist will unleash his wrath on believers, another facet of the sufferings is that the Great Tribulation is the point in time when God will punish the earth. While the Antichrist is hunting believers and persecuting Jews, God will punish the unbelievers who have rejected Him. Revelation 13–19 describes His judgments. Specifically, Revelation 14:9–11 promises eternal damnation for those who worship the Beast. Chapter 16 describes the seven bowls of wrath, which include sores, the waters becoming like blood, fierce heat from the sun, and darkness.
• Near the end of the Great Tribulation, the Euphrates River will dry up, allowing armies from the east to march toward Israel for war (Revelation 16:1–21). The Battle of Armageddon will pit nations against the armies of the Antichrist. Finally, Jesus and the armies of heaven will join the fight (Revelation 19:11–21). Earthly armies will be slaughtered. The Antichrist and his prophet will be thrown alive into the lake of fire. An angel will bind Satan and throw him into the bottomless pit, sealing him for one thousand years (Revelation 20:3).

implications for today

The Great Tribulation will be horrific. Between the warring nations, the Antichrist grasping for power, and God's wrath against the world, it is not a time anyone will want to live through. For believers in Christ of the church age, we don't have to. The rapture, which will happen sometime before the tribulation begins, will take Christ-followers away from the earth and God's judgment. After the rapture, people will come to a saving knowledge of Christ. But before the rapture, we have the opportunity to make sure we never see the Great Tribulation and to tell others how they can miss it as well.