There are two main parts to time immediately before Christ comes: the End Times and the Tribulation.
The end times are characterized by signs that are spoken of by Peter, Timothy, Jesus, Daniel, Isaiah, and in other books of the bible in both the New and Old Testaments. Links to many of those signs are on the right hand sidebar
The Tribulation begins when the Antichrist confirms a seven year covenant (treaty) with Israel. Dan 9:27, Dan 12:11. Then, a series of seven seals are opened.
The first four seals release a horseman as each are opened in turn:
White: the Antichrist, Rev 6:2
Red: War, Rev 6:3-4
Black: Famine, Rev 6:5-6
Pale/Chloros: Death, Rev 6:8
Fifth Seal: Death of Martyrs, Rev 6:9
Sixth Seal: Great earthquake/moon as blood/sun darkened, Rev 6:12
Seventh Seal: ushers in the next series of judgments. The Trumpets. These will be so harrowing there is silence in heaven for half an hour.
Trumpet 1: Hail and Fire burn up grass and 1/3 trees, Rev 8:7
Trumpet 2: Blazing mountain thrown into sea, 1/3 sea creatures die, Rev 8:8
Trumpet 3: Wormwood falls from heaven, poisoning 1/3 rivers, Rev 8:10
Trumpet 4: Removal of 1/3 light on earth, Rev 8:12
These judgments remove 1/3 of everything we need to live: water, vegetation, light. Thus ends the ‘easy’ part. Now God gets tough.
Trumpet 5: Scorpion-Locusts from the Abyss, five months torture from their stings, Revelation 9:1-12.
Trumpet 6: Four angels bound in Euphrates loosed and kill 1/3 mankind, Rev 9:14
Trumpet 7: Initiates Bowl judgments. “Great” Tribulation begins. This is when satan is cast out of heaven (Revelation 12) and he becomes so angry that he tries to kill the Jews, (Rev 12:12-13) but they flee to the wilderness (understood to be Petra in Jordan) (Rev 12:14) and so satan turns his hate and anger and frustration to the Christians. (Rev. 12:17)
Bowl 1: Painful sores upon those with the Mark, Rev. 16:2
Bowl 2: Sea into blood, all seas & creatures die, Rev. 16:3.
Bowl 3: All fresh water turns to blood, Rev. 16:4.
Bowl 4: Sun scorches people with fire, people curse God, Rev 16:5
Bowl 5: Antichrist’s throne & kingdom thrown into total darkness, Rev. 16:10
Bowl 6: Euphrates dried up, enabling Kings of East to assemble armies at Armageddon, Rev. 16:12.
Bowl 7: “It is done!” Earthquake so great every island and mountain passes away, 100lb hailstones fall upon men. Rev. 17:21.
The Harlot of the One World Religion is destroyed and the battle of Armageddon takes place when Jesus returns with his church in victory. He reigns for 1000 years! Revelation 17,18 and 19. Praise God!
Good links to more about the chronology with commentary and explanations:
The First Half of the Tribulation
The Tribulation Judgments
Tribulation Judgments: Are they sequential, natural, or supernatural?