It is written that Pythagoras became acquainted with the pentagram during his stays in Egypt and Babylon maybe around 554-533 BCE. Pythagoreans used it for recognition. To them, the pentagram was known as "Hugieia" which translates to health, soundness or wholeness and is also known as the Goddess of Health. More generally, it is said to translate to "divine blessing". It was also used an inscription on amulets.

With certainty, it is known that it was the official seal of the city of Jerusalem during the period 300-150 B.C. In medieval Jewish mysticism it is called The Seal of Solomon or Solomon's Shield. However, it is said that the reference to The Seal of Solomon is incorrect though usage was parallel with the hexagram. Amongst Hebrews the symbol stood for truth and ascribed to the five books of the Pentateuch. It was called the Pentalpha in Ancient Greece and was geometrically composed of five "A's".

It is sometimes referred to as the Eastern Star, identical with the morning star and the planet Venus as the war goddess Ischtar or Astarte. Up until the middle ages, Christians wore the pentagram to symbolize their religion. To Christians of that time, each point stood for the five wounds of Christ. Note that the star is popular with the military and can be seen on uniforms as well as the sides of tanks and fighter planes in the United States, Russia, China and other countries and also appeared on some of the crusaders knight's coats of armor during the middle ages. It then became associated with magick and the evil. In Nordic countries it was drawn on doors and walls as protection against trolls and evil. When turned so that two ends point upward, it represented the devil. However, in some traditions, the pentagram/pentacle worn with the two points upward means that they are second year initiates. For the Japanese, in their Art of Warfare it stands for fortresses.

Today, we Witches or Wiccans wear the pentagram as a symbol of our religious belief, like Christians wear a cross or Jews wear the Star of David. Each point of the star has a specific meaning:

The circle around the pentagram represents the God and Goddess. It is said to bring the wearer total intelligence, universal wisdom and protection. Of all the tools used in Witchcraft/Wicca, it is the most misunderstood. It has been used in ceremonial magick and ritual for thousands of years. It's energy is generally considered feminine and is used to consecrate objects such as amulets and charms. It is a   representation of the Goddess and traditional symbol of protection. The pentagram has become the official symbols of Witchcraft/Wicca.

The pentacle/pentagram is the tool of the north and is associated with earth. The pentacle is an altar tool made of a shallow dish inscribed with a pentagram.   When used as the sacred moon talisman, it is a disk of plain silver, wood or wax. It serves as the initial point of contact in drawing down the Goddess power from the moon. It is a source of psycho-electric energy during the waxing and full moon periods. The circle around the Pentacle represents power. It can also represent solar and lunar discs which are the male and female principles.

While I was studying the pentagram, I was made aware that the associations used often varies with the tradition followed. On some altars, the pentagram/pentacle sits in the north quarter which represents the earth qualities and is painted on a concave wooden disk.

Various traditions assign elements to different quarters. The same applies to colors. Some paths will put the earth element in the east, some to the south, and others to the north. Some associate the pentacle and green to the north quarter but, in some traditions, the pentacle is placed in the east and green placed in the south. Some traditions place a red candle to the east, green to the south, blue to the west and white to the north. Red is for the rising sun, green to the south because that's where food comes from, blue to the west because that's where the chalice was placed and white to the north for the Goddess.
A note, to the Druids, gray goes in the West.

It is also found that the below associations are the most widely agreed upon for magick and coincide with the teachings of the Qabalah, the Key of Solomon, the Golden Dawn, the Ordo Templi Orientus (O.T.O.), most tarot decks and the general human concept of color perception (red sits opposite green, yellow/yellow-orange opposite of blue/violet, as placed on the color wheel).