![book cover](https://launchdarkly.com/static/ebook-cover-4ed2cebfdecc8fb47424e8ec6cc9c947.png)
A feature flag is like a powerful “if ” statement:
if(enableFeature(one.click.checkout, {...}))
then /*show the one-click checkout feature */
else /* show the old feature/
Deploy != Release
Test in Production
Percentage Deployments
A/B Testing
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