Its five points represent (starting at the top and moving clockwise) spirit, fire, water, earth, and air.   The fact that "spirit" is at the topmost point means that all of the earthly elements are subject to the power and influence of "otherworld;" the fact that there is a circle connecting all five means that they are interwoven, the natural elements with the spiritual.

The four "earthly" points   —   representing the elements   —   remind us that we don't "leave this world" when we find the path; we still hold jobs, pay our child support, and get stuck on the freeway ... just like everybody else.   The "spirit" point reminds us that we should look for the spiritual significance of otherwise mundane events.

Fire, water, earth, and air were the traditional "four elements" of alchemy.   The "fifth element" (the akasha or "quintessence"), the spirit, was used to explain phenomena that were otherwise unexplainable.

Carl G. Liungman explains says that "If one knows the ecliptic and can pinpoint the present position of the planets in relation to the fixed star of the zodiac, it is possible to mark the exact place in the 360 degrees of the zodiac where the 'morning star' first appears shortly before sunrise after a period of invisibility.   If we do this, waiting for the "morning star" to appear again 584 days later (583.9211 days, to be exact   —   the orbital time of Venus) and mark its position in the zodiac, and then repeat this process until we have five positions of Venus as the morning star, we will find that exactly eight years plus one day have passed. If we then draw a line from the first point marked to the second point marked, then to the third, and so on, we end up with a pentagram." (Dictionary of Symbols, 1991, pp. 333-334). For additional reading on this very interesting phenomenon, click here.

The followers of Archimedes are said to have worn a pentagram because it represented angles and mathematical relationships.   It is believed that Christians once wore the pentagram as a symbol of their faith (representing the star of Bethlehem, perhaps).