where it’s at

where it's at

1. The place where things are most exciting, active, or lively. I've traveled all over the world, and, if you're looking for a party, Ibiza is definitely where it's at. For the last few decades, Austin has been where it's at for the independent music scene in the southern United States.
2. The place, field, industry, etc., where there is the most activity and opportunity. For people who want to produce online content, streaming services are where it's at right now. If you're looking for the most lucrative and plentiful job opportunities, computer programming is where it's at.
3. That which is currently very fashionable, trendy, or popular. Big, broad suits are so last-century—well fitted trousers, jackets, and shirts are where it's at right now. When you're building or remodeling your home, energy-saving features like triple-glazed windows and solar panels are where it's at.
Farlex Dictionary of Idioms.

where it’s at

phr. what one is aiming for; what is needed. (This does not refer to a place.) Keep on trying. That’s where it’s at!
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions
See also:
  • know where is at
  • where it's at
  • where the action is
  • heather
  • set the heather alight
  • set the heather on fire
  • set the Thames alight
  • set the Thames on fire
  • set the world alight
  • Thames