The apple you are referring to is likely the “Granny Smith” apple. This is a type of apple that is typically eaten raw or used in general cooking. It is in season from December to March, although it can often be found year-round in many parts of the world. Granny Smith apples are known for their bright green skin, tart flavor, and firm texture, which makes them a popular choice for baking and cooking. They are also a popular snack, both on their own and when paired with cheese or caramel.