Pentacle

The pentacle (five pointed star, surrounded by a circle) symbolizes the figure of man with outstretched arms and legs. It stands for an integral personality; human/Microcosm; endless; power of perfection. In witchcraft, a reverted pentacle represents the devil's goat, and the witches foot. It's a sign of reversal of man's true nature.
(The figure stems from the alchemy and represents the unity of five elements: earth, fire, air, water and ether/quintessence; thus it also is a symbol for the super-natural.)
Pentacles are also often associated with creativity, material possessions, and wealth.

In most Tarot decks, Pentacles was (or is) one of the four suits of the Minor Arcana. In the Toth and Rider/Waite decks, the name has been changed into 'Disks.'

Some more on its symbolic meanins:

Protection and Warding: One of the most common uses, the pentacle is believed to offer protection against negative energies, evil spirits, or harmful influences. The circle is thought to contain and amplify this protective power.

The Five Elements: In many traditions, each point represents one of the classical elements - earth, air, fire, water, and spirit (or aether). This makes it a symbol of elemental balance and natural harmony.

The Human Form: The five points can represent the human body - head, arms, and legs - symbolizing humanity's place in the cosmos and the connection between human and divine.

Microcosm and Macrocosm: The pentacle represents the relationship between the individual (microcosm) and the universe (macrocosm), showing how personal spiritual development reflects cosmic principles.

Venus and Divine Feminine: Astronomically, Venus traces a pentagram pattern in its orbit relative to Earth. This connects the symbol to love, beauty, and feminine divine energy.

Mathematical Perfection: The pentagram contains the golden ratio throughout its geometry, making it a symbol of divine proportion, harmony, and mathematical perfection in nature.

Wiccan and Pagan Spirituality: In modern paganism and Wicca, the pentacle is a primary religious symbol representing earth-based spirituality, the goddess, and the interconnectedness of all life.

Christian Symbolism: Historically, early Christians used the pentagram to represent the five wounds of Christ or the five senses that should be dedicated to God.

Inverted Meanings: When inverted (point down), interpretations vary - some see it as representing matter over spirit, while others view it negatively as associated with darker practices.

The meaning often depends heavily on cultural context, religious background, and whether it appears upright or inverted.