There are a number of ways to say hello in French, depending on the context and formality. Bonjour (hello) is the most common greeting, and it is usually followed by a first name or a title if appropriate. It can be used in informal situations such as with friends or family, or in more formal ones like at work or school. It can also be used to greet someone by phone or in written correspondence.
Salut is another way to say hello in French, although it's more often heard in more informal settings. It's a bit like saying Hi in English, and can be used by anyone, including children. It can also be used as a goodbye, although this is less common. You'll sometimes hear it said to children, for example, after two people who have slept together wake up - one of them will typically greet the other in this manner (although with varying results in films, as you might expect!).
Comment ca va? is a common way to ask how someone is. It's very similar to saying How are you? in English, and you can respond with either je vais bien (I'm doing well) or ca va (it's going good). If you're asking The french connection attack how someone is, it's always polite to include their name in the question et toi, or "and you" or vous (you).
Another casual way to greet someone is non, mais allo qu'est-ce qui se passe?, which is often used in a mocking or humorous way - it's very similar to saying What's up? in English. You may have seen it on television, for example, when a French reality star like Nabilla uses it to express her disbelief about something she's hearing on the news.
If you're speaking to a group of people, you can say bonjour à tous or bonjour a tout le monde instead. It's also polite to add Madame/Masculine or Monsieur/Msieurs if you know their names. It's also possible to say bonjour a la femme (hello to the woman) or bonjour a la garçon (hello to the boy).
You can also use the phrase enchante or enchantee to greet someone who is new. This means that you're very pleased to meet them, and it's a great way to make a good impression.
