
An orange slice is a wheel of fresh orange, carrying flesh, peel and aromatic oil at once.
Dropped into the drink rather than perched on it, a slice releases a little oil from the peel and a faint bitterness from the pith. Both build the longer the glass stands. That suits a spritz or a long build, and does little in a drink meant to be finished quickly.
Half an orange wheel
Does the same job.
Lemon or lime wheel
Works just as well. Only the color, aroma and bitterness change.
Orange wedge
Sliced lengthwise to squeeze into the glass and sit on the rim. Use it if shape is not crucial.
Orange twist
A last resort. The colored peel gives great aroma but adds no fruit or color.
Cut to order: a cut face dries and curls within a couple of hours. Whole oranges keep far longer than most bars need. Unwaxed fruit is worth finding if the peel goes into the glass.