Is it normal for a child to have an imaginary friend?
Yes — and it is far more common than most parents assume. Research suggests a substantial proportion of children, by some estimates around half or more, have an invented companion at some point, usually between about three and eight years old.
It is associated with strengths, not problems. Studies have generally found that children with imaginary companions tend to score well on measures of creativity and narrative skill, and often show stronger theory of mind — the ability to understand that other people hold beliefs and feelings different from their own. Inventing a character with independent opinions is direct practice at exactly that. They are not typically lonelier or less socially skilled than other children, which is the usual worry.
What the friend is doing for them varies. It can be a way to rehearse social situations safely, to express feelings that are hard to own directly — the friend is scared of the dark, not me — to have control in a world where they have little, or simply to enjoy a good story. Some children use the companion to test rules, which is why the friend is often the one who wanted the biscuit.
How to respond: playing along is fine and costs nothing. So is gently declining to be governed by the friend's demands. You do not need to insist the friend is real, and you do not need to correct the child either — most children of this age know perfectly well that the companion is pretend, even while taking it seriously.
When to seek advice: if the child seems genuinely frightened of the companion, believes it is real in a way they cannot step out of, describes it commanding them, or if it appears alongside marked withdrawal or distress, that is worth raising with a health visitor or GP.