A pentagram is a five pointed star. Traditionally, the five points of the star represent the four elements (Earth, Water, Fire, and Air) and Spirit. An upright pentagram represents the triumph of spirit over matter, while an inverted pentagram represents the descent of spirit into matter. Pentagrams are often used in magick, usually to invoke or banish elemental energies when casting a circle. Not to be confused with a pentacle, which is simply a pentagram with a circle around it.

Historical associations of the pentagram include the five senses, the five fingers, the five wounds of Christ, and astrological representation of the five planets: Jupiter, Mercury, Mars and Saturn, and Venus. Modern day associations include: the upright pentagram (or pentacle) as a symbol of adherents to Wicca/Paganism/Witchcraft (much as a Christian would wear a cross as a symbol of their faith). An inverted pentagram with a goat's head, called the Sigil Baphomet, is the official symbol for the Church of Satan.

A five pointed star witha circle around it. These can either be pointing up or down, depending on religion. An upright star is used mainly by wicca, but it was also used as a christian symbol, in christianity its meaning is of the five scars of Jesus. One on each arm and leg and one on his side.The only band to my knowledge that uses this symbol is the hard rock band Godsmack. An inverted star is used in Satanism. It represents either pointing toward Hell or a goats head (depending on how you look at it.) Some heavy metal bands such as Slayer and the newer Drowning pool use this symbol.

a mathematical symbol invented by Pythagoras back in the day that was mistaken as a pagan/satanist icon by christians. As a (rather ironic) result, pagans and satanists now use it as a religious symbol

Most commonly confused with satanism.
Please notice that it is NOT unless it is inverted.
It is used in warding evil spirits, religious (the five points of Christ), and the elements (spirit, fire, water, air, earth {Spirit ALWAYS on top unless inverted to show spirit ruling over elements})

A five pointed star without a circle around it. Sometimes seem as inverted with the baphomet head it represents satanism. However, there is nothing negative about it.

A 5 sided star that appears upsidedown. Not to be confused with the wiccan "Penticle" which is a right side up 5 sided star and holds totally different significance. Primarily used in the Satanic or Sumarian religions as a representation of anit-Humanity (while the penticle represents humanity therefore it is right-side-up) or the god baphomet

A five pointed star that symbolizes the Wicca religion. Often confused wit a Satanic symbol. The pentagram is NOT Satanic. If the top point is pointing down, it is a Satanic symbol. However if the top point is pointing up, it is a sign of Wicca. The top point is always Spirit, because the Spirit rules over the Element. The other four points are the for basic Elements: Earth, Fire, Water, and Air.