Today's Parola del Giorno is the verb expression entrare in vigore, which means to come into force or to come into effect.

It is usually used to describe a new law or proclamation that has come into force.  

See the expression used below:

Ieri è entrata in vigore una legge che vieta a chi ha meno di 14 anni di entrare nei locali dopo una certa ora. Penso che sia una buona legge, ci voleva proprio.

Yesterday a law came into effect that prohibits those under 14 years old from entering clubs after a certain hour.  I think this is a good law that was really needed.