FTF-101

Toggles

A switch in your code, decided while it runs

A feature toggle is a named switch your code checks before running something new — the new code ships turned off, and goes live when the toggle says so.
Every toggle has a switch: on or off. It's changed in FTF, not in the code — no redeploy, and it can be switched off again in seconds if something goes wrong.
A toggle can also have attributes: which customers it's on for — only brands A and B, only claims over $10,000. Your code passes what it knows; the toggle decides (business scenarios).
Its name says who owns it: your company's prefix, the application, the toggle — acme.web.new_checkout.
The code asks the same way everywhere. Each environment's own switches and attributes give the answer.

if (await ftf.isEnabled("acme.web.new_checkout", { brand })) {
  showNewCheckout();   // the new feature
} else {
  showCheckout();      // what customers have today
}