I found a recipe for toffee which I'd like to try and make. I've never done it
before. It's simple enough, but the ingredients says 2 cups white sugar. Are
they talking granualted sugar or confectioners sugar?

It also says:

"In a large heavy bottomed saucepan, combine the butter, sugar and salt. Cook
over medium heat, stirring until the butter is melted. Allow to come to a boil,
and cook until the mixture becomes a dark amber color, and the temperature has
reached 285 degrees F (137 degrees C). Stir occasionally."

Should I buy myself a candy thermometer before I attempt this or will eyeballing
the mix until it reaches the dark amber color be sufficient. Thanks.