The prepositions à and de

The prepositions à and de are the two most common prepositions in French. The preposition à can be used when expressing where you are or where you're going:

Je vais à l’école

I'm going to school

Mes cousins vivent au Canada

My cousins live in Canada

Nous voyageons à Paris

We're travelling to Paris

And for saying what time something happened or is happening, and in some other time expressions:

Je suis arrivé à 10 heures

I arrived at 10 o'clock

Nous y allons au printemps

We're going there in the spring

Common uses of the preposition de include expressing possession:

C'est le livre de Paul

It's Paul's book

And expressing where you come from or where you are travelling from:

Je viens de Manchester

I come from Manchester

Nous revenons de Paris le 7 avril

We're coming back from Paris on 7 April

Both à and de are often used to introduce an infinitive :

Il a commencé à pleuvoir

It started raining

Elle a promis de venir tout de suite

She promised to come straightaway