There are three common types of mustard seed you're likely to find in your local grocery store, including yellow, brown, and black. Each one has a slightly different flavor, though you can use them interchangeably while cooking. Yellow mustard seeds are the mildest of the three and are ideal when you're looking to add a more mild flavor and tame heat to your food. Generally, use twice as much of these as you would of the other two kinds. Brown mustard seeds have a medium intensity, hotter than yellow mustard but not quite as potent as black mustard. They have an earthy taste and are a good all-around pick for most foods. Black mustard seeds are the strongest and hottest. Make sure to use them in moderation when cooking. Even if you like spices, they can quickly overpower a dish.