Dilly asks for a birthday for two reasons.
1. A parent's yes
Children under 13 can only use Dilly after a parent or guardian says yes. The birthday tells Dilly whether that step is needed. See A parent says yes first.
2. A grade suggestion
Dilly uses the birthday to suggest a grade. See How does Dilly guess my child's grade?
What Dilly keeps
Dilly keeps your child's first name, birth date, school grade, companion and nickname. It uses these to run Dilly for your family and show you how your child is doing. Dilly does not sell it and does not share it for ads. See What Dilly keeps.
Only a first name
Dilly asks for a first name, not a full name.
