A muddler is a tool that bartenders use to mix cocktails. It's basically a long rod with a flat end that muddles, or crushes, the ingredients in a cocktail. This helps to release their flavors and aromas so they can be properly mixed together.
Muddlers come in different sizes and shapes, but they all serve the same purpose. Bartenders will use them to muddle everything from fruit and herbs to spices and even ice. If you're making a cocktail that calls for muddled ingredients, make sure to get yourself a muddler!