A classic of the classics in France !!!!The best known is the hollandaise, a smooth, light-as-a-feather sauce that is also addictively rich. It's a bit like a hot, looser mayonnaise, and like mayonnaise is perfect accompaniment to poached fish and vegetables. Hollandaise sauce can be flavoured with all sorts of other ingredients, most famously perhaps with tarragon to create beanaise sauce – the classic French accompaniment to grilled steak. Hollandaise and other emulsions can be made with melded butter, but I prefer to use clarified butter as it gives a purer, smoother flavour.
French sauces should not intimidate you. After you've made a sauce one time you will see how simple it can be. And the name can add elegance to your meal. Try calling macaroni and cheese, Des Pates à la Sauce Mornay, and see if your family notices the difference.