Why are greek vases valuable sorces of information to archaeologists?

All pottery is important to archaeologists, because it is one of the materials which survives hundreds or even thousands of years to be dug up today, along with stone and some metals, and in contrast to wood and cloth, which decay and only survive in very exceptional cases. Unlike stone and metal, however, pottery can inform archaeologists about daily life. Pottery is used for so much - cooking, storage, transporting goods, eating and drinking, and so much else - that is it widely used by everyone, not just elites of a society. Since it is relatively cheap and easy to create, there's an awful lot of it to be found, and archaeologists have create typologies of certain types of vessel - that is, tracking changes over time in vessel shapes - which allows them to have some idea of the chronology of a site or layer (context) where objects are found. This enables archaeologists to build up a picture of how a site may have changed over time. Painted wares can provide more accurate dating, since we know the rough dates of certain painted styles. Volumes and types of pottery can give us an idea of whether a settlement grows or shrinks over time, or if it becomes wealthier or poorer. If, for example, pottery has been imported (which we can sometimes tell by the style of pottery, or if not sometimes by chemically analysing it or looking at what minerals it contains), then this implies that the settlement has good which it has sold in exchange for these vessels and thus that it is fairly well off.