What are books in Go Fish?

Whenever you hold all four of a rank, lay the book face up in front of you immediately.

Section 4: Gameplay

On your turn, ask one specific player for one specific rank — "Marco, do you have any sevens?"
You must already hold at least one card of that rank. This is the rule most often forgotten.

They have it: they hand over every card of that rank, and you go again.
They do not: they say "go fish". You draw one card from the pond and your turn ends — unless you draw exactly the rank you asked for, in which case many households let you go again.

Whenever you hold all four of a rank, lay the book face up in front of you immediately.

If you run out of cards, draw a new hand from the pond if any remain. The game ends when all thirteen books have been made.

On your turn, ask one specific player for one specific rank — "Marco, do you have any sevens?"
You must already hold at least one card of that rank. This is the rule most often forgotten.

They have it: they hand over every card of that rank, and you go again.
They do not: they say "go fish". You draw one card from the pond and your turn ends — unless you draw exactly the rank you asked for, in which case many households let you go again.

Whenever you hold all four of a rank, lay the book face up in front of you immediately.

If you run out of cards, draw a new hand from the pond if any remain. The game ends when all thirteen books have been made.