You are going to see “Il faut” a lot, especially in French news articles, as everyone tells you what must be done, what needs to be done, and what is required.
Devoir vs. Falloir – Devoir can be used with all personal pronouns: je, tu, il/elle/on, nous, vous, ils/elles:
- Je dois partir – I have to leave
- Nous devons attendre – We have to wait
Devoir when followed by an infinitive, expresses an obligation, probability, or supposition.
Falloir can only be used with one pronoun: il (impersonal ‘it’):
- Il faut partir – It must go
- Il faut que je te parle – I have to talk to you (literally: It has to that I speak to you)
Falloir is stronger and somewhat more formal than devoir ; it expresses necessity. Falloir can be used with an infinitive or the subjunctive. Because it’s an impersonal verb, falloir does not conjugate for different subjects. In order to specify the person who needs to do something, you can either use the subjunctive or an indirect object pronoun with the infinitive.