Know somebody/something backwards

Pro Tip 1/3

Colloquial Use

This phrase is casual and used more in spoken than written English, often in familiar or informal situations.

Ask Jerry about car engines, he knows them backwards.

Pro Tip 2/3

Expert Knowledge

The phrase suggests a deep, thorough understanding, usually from experience or long-term involvement.

She can fix any bug; she knows the code backwards.

Pro Tip 3/3

Not Literal

It's a figurative expression, meaning there is no actual 'backwards' knowledge involved.

You won't stump him on history questions; he knows it backwards.