The chalice is one of the most iconic images of European art and religious imagery. The most famous is the Holy Grail of Christ, the cup which was used at the Last Supper. An integral part of the English Arthurian myth cycle and British isles folk religion, the chalice is an ancient image that resonates strongly still today. Much of modern pagan tradition is derived from attempts to reconstruct (or reinvent, in many cases) the ancient worship practices of pre-Christian Europe.
One of the major symbols is the cup or bowl/cauldron. A chalice is simply a cup with a footed base, though the term sounds fancy. Any cup could work for a ritual chalice, even your favorite coffee mug. It is a little more fuzzy when you start blurring the line between cup/bowl/cauldron. Because the cauldron is a ritual item in its own right. And the bowl has its own storied history of iconography around the world. It is the chalice that is used for the symbolic enacting of the Great Rite of Wicca rituals (the Great Rite being the sexual union between the God and the Goddess), serving as the female half of the rite. (The male half is the athame. For more information about the athame, please see the next post in this series.)
The chalice is the shared cup between the coven during ritual feasting in some rites. It is also symbolic of the cup that the Daughter of Dea pours Her Spirit into in the holy rite of sacrifice which sustains the whole of existence within Filianic and Déanic mythos. It is an object that is described by some as a direct descendant of the Communion cup of the Catholic Christian mass (worship service) and supposed to symbolize both the cup that caught the blood of Christ from his wounds and the cup from the last supper.
Within many pagan and occult systems, the chalice is associated with water. This can be seen in most tarot decks, actually. It is associated with the direction of west. And, as mentioned earlier, it is associated with femininity. It is also associated with the subconscious mind, the spirit, and psychic activity.