Today's census figures will focus on international migration, ethnic groups and religion - and the Welsh language.
Some parents like Rhian Cecil hope it'll lead to more Welsh medium and bilingual schools over the next ten years.
"It's really important for us as Welsh speakers to be stood up and counted".
"Hopefully all the figures can help local councils create more provision".
More top news
RAF veteran Andy Davies says the Royal British Legion helped him get back on his feet after problems with alcohol.
Lucy has the latest weather forecast for Wales
Plaid Cymru leader Leanne Wood has said her MPs won't back English votes for English laws until Wales gets an extra £1.2 billion a year.