What's the difference between 'tous' and 'tout'?

The main thing to remember here is that what's basically one word can be used in different forms - as an adjective, noun or even adverb. The most common ones are adjective and noun, so that's what we'll cover now. You'll probably be most likely to want to use 'tout' or 'tous' to mean 'every' or 'all' - this is an adjective, and comes before the noun. The rule here is that 'tout' is singular, used before singular nouns (like 'tout le pain') but 'tous' is used before plural ones ('tous mes amis'). That's all you need to remember! On the other hand, if you want to use it as a noun, you'll probably be wanting to say either 'everyone' or 'everything'. 'Tout' with a t always means everything, and 'tous' means everyone - and this s is pronounced, unlike the adjective forms which both sound the same.