Signature cocktails are noted for having fresh ingredients as part of the recipe, requiring the mashing of those ingredients to better infuse the taste to the alcohol and/or to release the desired aromas.  Muddlers are an essential tool for any professional bar hero to accomplish this.

Muddlers come in a variety of sizes and designs, but the purpose cannot be denied.  Muddlers will have a broad, flattened end in order to mash the fruit, herbs, etc., against the bottom of the mixing glass or shaker.  Some modern bar spoons have incorporated a muddler on the far end of the spoon, but the use of these is absolutely at the preference of the bar hero making the drink.

If a muddler is not available, consider using a morter and pestle, wooden spoon, or a meat pounder to get the desired effect.