What does Daniel mean by the time of the end?
In Daniel's prophecies, "the time of the end" is the final, climactic period of history just before the Lord's return, when the man of sin (the antichrist) rises to full power, defiles God's temple, persecutes the saints, and is finally cast down through a series of divinely fixed time periods leading to Michael's victory and the deliverance of God's people.
Daniel speaks of "the time of the end" as the closing chapter of this present age, when wickedness comes to its fullness and a king of fierce countenance stands up, understanding dark sentences and empowered by Satan himself. This is not a vague or distant idea to Daniel; it is a specific season marked out by God with exact numbers of days. Satan's war in heaven against Michael and the defiling of the heavenly sanctuary lasts twenty three hundred days, and from the moment the daily sacrifice is taken away on earth to the setting up of the abomination of desolation there are one thousand two hundred ninety days. These count downs frame the time of the end as a season with a beginning, a middle, and a determined finish.
Within that time of the end, the man of sin, the antichrist, confirms a covenant with many for one week, that is, seven years, and in the middle of that week causes the sacrifice and oblation to cease, setting up the abomination that makes desolate in the holy place. This is also described as "a time, times, and an half," the period in which the power of the holy people is scattered before all these things are finished. So the time of the end includes a seven year covenant, broken at its midpoint, followed by three and a half years of great tribulation in which the saints are worn out by the antichrist's fierce persecution.
Daniel also shows that during this time of the end, those who understand among God's people will instruct many, yet many will fall by sword, flame, captivity, and spoil; some of the wise will fall so that they may be tried, purged, and made white, because it is yet for a time appointed. Meanwhile the king of fierce countenance exalts himself above every god and prospers until the indignation is accomplished, for what is determined must be done. The time of the end also brings international war: the king of the south pushes at him, and the king of the north comes against him like a whirlwind, overrunning many lands, even as tidings out of the east and north trouble him and drive him to his final destruction, where none shall help him.
So for Daniel, the time of the end is the appointed, numbered season in which Satan's rebellion in heaven, the antichrist's rise and covenant breaking on earth, the great persecution and purging of the saints, and the clash of kingdoms all converge, ending with the antichrist's downfall and Michael's deliverance of God's people who are written in the book.
The scriptures
And in the latter time of their kingdom, when the transgressors are come to the full, a king of fierce countenance, and understanding dark sentences, shall stand up. And his power shall be mighty, but not by his own power: and he shall destroy wonderfully, and shall prosper, and practise, and shall destroy the mighty and the holy people. And through his policy also he shall cause craft to prosper in his hand; and he shall magnify himself in his heart, and by peace shall destroy many: he shall also stand up against the Prince of princes; but he shall be broken without hand.
Yea, he magnified himself even to the prince of the host, and by him the daily sacrifice was taken away, and the place of his sanctuary was cast down.
And at that time shall Michael stand up, the great prince which standeth for the children of thy people: and there shall be a time of trouble, such as never was since there was a nation even to that same time: and at that time thy people shall be delivered, every one that shall be found written in the book.
And from the time that the daily sacrifice shall be taken away, and the abomination that maketh desolate set up, there shall be a thousand two hundred and ninety days.
But I will shew thee that which is noted in the scripture of truth: and there is none that holdeth with me in these things, but Michael your prince.
And such as do wickedly against the covenant shall he corrupt by flatteries: but the people that do know their God shall be strong, and do exploits. And they that understand among the people shall instruct many: yet they shall fall by the sword, and by flame, by captivity, and by spoil, many days. Now when they shall fall, they shall be holpen with a little help: but many shall cleave to them with flatteries. And some of them of understanding shall fall, to try them, and to purge, and to make them white, even to the time of the end: because it is yet for a time appointed. And the king shall do according to his will; and he shall exalt himself, and magnify himself above every god, and shall speak marvellous things against the God of gods, and shall prosper till the indignation be accomplished: for that that is determined shall be done. Neither shall he regard the God of his fathers, nor the desire of women, nor regard any god: for he shall magnify himself above all. But in his estate shall he honour the God of forces: and a god whom his fathers knew not shall he honour with gold, and silver, and with precious stones, and pleasant things. Thus shall he do in the most strong holds with a strange god, whom he shall acknowledge and increase with glory: and he shall cause them to rule over many, and shall divide the land for gain.
And he shall confirm the covenant with many for one week: and in the midst of the week he shall cause the sacrifice and the oblation to cease, and for the overspreading of abominations he shall make it desolate, even until the consummation, and that determined shall be poured upon the desolate.
And one said to the man clothed in linen, which was upon the waters of the river, How long shall it be to the end of these wonders? And I heard the man clothed in linen, which was upon the waters of the river, when he held up his right hand and his left hand unto heaven, and sware by him that liveth for ever that it shall be for a time, times, and an half; and when he shall have accomplished to scatter the power of the holy people, all these things shall be finished.
From the books
This answer is drawn from these passages in the Mary Banks Faith Library.