How do you know when to use 'de' or 'à' in French?

In French, 'de' and 'à' are prepositions that are used to indicate various relationships between nouns, verbs, and other elements of a sentence. The choice between 'de' and 'à' can depend on many factors, including the meaning of the verb, the nature of the nouns involved, and the context in which the sentence appears.

The preposition 'de' is generally used to indicate possession or origin, and is often used after verbs such as 'avoir' (to have), 'venir' (to come), and 'être' (to be), while the preposition 'à' is typically used to indicate direction or location, and is often used after verbs such as 'aller' (to go), 'venir' (to come), and 'habiter' (to live).

However, there are many exceptions and nuances to these general rules, and the use of 'de' and 'à' can be quite complex. To become more proficient in using these prepositions, it is important to study their usage in context and to practice using them in various types of sentences and situations.