Avoir besoin de, devoir, falloir - which is appropriate when?

Question

I *think* I understand when to use “avoir besoin de” or “devoir”, but how/where does “falloir” work? (Note: I asked a similar question in the lesson on “falloir”)

Céline Pickard · Accepted Answer

Bonjour Sheri,
In French, you will use "falloir" / "il faut" to express a general necessity or obligation.

Il faut manger des légumes = You must eat vegetables
Il faut manger pour vivre = You need to eat to live

Versus
J'ai besoin de dormir = I need to sleep
-> implies a personal need
Je dois dormir = I must sleep
-> implies a strong sense of obligation
 
I hope this is helpful.
Bonne journée !