What does "walk-in" mean?

When a library programme page says "Registration is not required. Please walk in.", you do not need to sign up online; just go on the day.

Admission depends on space and is first come, first served, so arrive about 10 minutes early. Attendance is taken by scanning the QR code at the venue with the NLB Mobile app; if you bring children, add their profiles in the app first. Some programmes require a parent or caregiver to stay with the child throughout.

Also, for programmes that do need registration, seats of latecomers may be released to people waiting on site.