Nuts are generally roasted to improve their taste, aroma and crunchy texture. Roasting is defined as cooking using dry heat, which cooks the food evenly on all sides. Most nuts are roasted without their shell, except for pistachios, which are often roasted in-shell. Meanwhile, raw nuts have not been roasted.
Roasting methods are sometimes used to separate the shells of nuts from their kernels. This is a common method of shelling cashews and the reason why they’re almost never sold raw.