A pressed sandwich is a sandwich compressed to bring its filling and bread together. It may be heated in a sandwich press or skillet, or weighted while cold, depending on the recipe.
Hot versions can develop a crisp exterior and melted filling. Cold pressed sandwiches are often made ahead so that the layers hold together when sliced. Panini are one familiar example of sandwiches that may be served pressed and toasted, but not every pressed sandwich is a panino.