A Pentagram is a mullet of five points voided and interlaced, commonly used in period heraldry. A Pentacle is a similar symbol, correctly blazoned A mullet voided and interlaced within and conjoined to an annulet.
It can be found in Christian churches like Notre Dame de Paris where it symbolizes the five wounds of Christ sustained during the crucifixion. It was also used to represent other ideas, such the five knightly virtues. In the poem Sir Gawain and the Green Knight, Sir Gawain bore a pentagram upon his shield.
Pentagrams in the SCA
Both the pentagram and the pentacle are used by modern Pagans as a religious symbol, (usually with a single point upward) representing the Five Elements. The popular association of a pentagram reversed (that is, with two points upwards) with Satanism led to this charge being placed on SCA College of Heralds' list of restricted charges in 1973. However, this decision was reversed in 2009, following the presentation of new arguments and evidence, and both the pentagram and pentacle, are now permitted.