What does the term "float" refer to in bartending?

In bartending, the term "float" specifically refers to the technique of layering a liquid ingredient on top of another without mixing them together. This is often achieved using a bar spoon, where the back of the spoon is used to gently pour the second liquid so that it rests atop the first. This technique creates visually appealing layers in cocktails, allowing for a striking presentation and distinct separation of flavors.

For instance, when making a cocktail such as a Pousse Café, different colored liqueurs can be floated to create layers that remain distinct due to their varying densities. This skillful layering is a hallmark of many classic drinks, showcasing both the bartender's technique and the aesthetic appeal of cocktails.