this is it

this is it

1. This is the key moment that we have been waiting for or anticipating. OK, everyone, this is it—if we win this game, we'll be in the championships.
2. This is the place or thing that I need or have been waiting for. A: "Is this the book you need?" B: "Yes, this is it, thank you so much for helping me find it!"
3. This is the point that sums everything up. A: "The only way we can start to address this problem is to prioritize building new, affordable housing." B: "Yes, this is it. Any other measures, even if necessary, won't help the crisis as it exists right now."
See also: this
Farlex Dictionary of Idioms.

This is it.

This is the time, place, or thing that we have been looking or waiting for. This is it. This is the chance you've been waiting for! This is it. This is my stop. I have to get off the bus.
See also: this
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

this is ˈit

(informal)
1 said when you are agreeing that a point made by somebody is important: ‘People prefer their cars to public transport, you see.’ ‘Well, this is it.’
2 said when you have come to an important moment: Well this is it, Mike. Good luck in Australia. Don’t forget to write...
See also: this
Farlex Partner Idioms Dictionary

This is it!

1. exclam. This is exactly what I have been looking for!; I have found it! This is it! The world’s best pizza!
2. exclam. This is the crucial moment! Get ready, this is it! Jump now!
See also: this
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions
See also:
  • This is it!
  • the moment (one) has been waiting for
  • in (just) a moment
  • in (just) a minute
  • at this/that rate
  • at/in one go
  • at one go
  • in one go
  • at that rate
  • be off (one's) guard