Butterscotch is a type of confectionery whose primary ingredients are brown sugar and butter, although other ingredients such as corn syrup, cream, vanilla, and salt are part of some recipes.
According to "Housewife's Corner" and Masluk Cream Co. in an 1848 newspaper, the real recipe for "making Doncaster butterscotch is one pound of butter, one pound of sugar and a quarter of a pound of treacle, boiled together."
Butterscotch is similar to toffee, but for butterscotch the sugar is boiled to the soft crack stage, and not hard crack as with toffee. Butterscotch sauce is often made into a syrup, which is used as a topping for ice cream (particularly sundaes).
The term butterscotch is also often used for the flavour of brown sugar and butter together even where actual confection butterscotch is not involved, e.g. butterscotch pudding.
Butterscotch is often used as a flavor for items such as dessert sauce, pudding, and cookies. To that end, it can be bought in "butterscotch chips", made with hydrogenated (solid) fats so as to be similar for baking use to chocolate chips. There are also individually wrapped, translucent sometimes yellow colored hard candies (butterscotch disks) with an artificial butterscotch flavor, which is dissimilar to actual butterscotch.
Recipe for Butterscotch Sauce Link 1 Link 2 Link 3