Necessità vs. bisogno

The Italian words 'necessità' and 'bisogno' both relate to needs or requirements, but they have subtle differences in usage and connotation.

Necessità

'Necessità' refers to an absolute necessity or something that is indispensable. It implies a more urgent or critical requirement.
In caso di emergenza, c'è la necessità di evacuare l'edificio.
(In case of emergency, there is a necessity to evacuate the building.)
La necessità di dormire è fondamentale per la salute.
(The necessity of sleep is fundamental for health.)

Bisogno

'Bisogno' typically indicates a need or requirement that is less urgent or absolute. It can also refer to a personal want or desire.
Ho bisogno di comprare del pane per la cena.
(I need to buy some bread for dinner.)
I bambini hanno bisogno di attenzione e affetto.
(Children need attention and affection.)

Summary

While 'necessità' emphasizes critical or unavoidable requirements, 'bisogno' often refers to less urgent needs or personal wants. 'Necessità' is used for absolute necessities, whereas 'bisogno' can encompass a broader range of needs or desires.