The winged symbol now associated with Zoroastrianism known as the Faravahar has its origins in an older symbol of a winged disk without a human figure within it. This older symbol, more than 4000 years old and found in both Egypt and Mesopotamia, was commonly associated with the sun and deities strongly connected with the sun. It also represented power, particularly divine power, and it was used to reinforce the concept of god-kings and divinely appointed rulers.
Assyrians associated the winged disk with the god Shamash, but they also had a version similar to the Faravahar, with a human figure within or emerging from the disk, which they associated with their patron god, Assur. From them the Achaemenid Emperors (600 CE to 330 CE) adopted it as they spread Zoroastrianism throughout their empire as the official religion.
The exact meaning of the Zoroastrian Faravahar in history is debatable. Some have argued that it originally represented Ahura Mazda. However, Zoroastrians generally consider Ahura Mazda to be transcendent, spiritual and without physical form, and for most of their history they did not artistically depict him at all. More likely, it continued to primarily represent divine glory.
It may have also been associated with the fravashi (also known as the frawahr), which is part of the human soul and acts as a protector. It is a divine blessing granted by Ahura Mazda at birth and is entirely good. This is different from the rest of the soul, which will be judged according to its deeds on the day of judgment.
Today, the Faravahar continues to be associated with the fravashi. There is some debate as to specific meanings, but what follows is a discussion of common general themes.
The central human figure is generally taken to represent the human soul. The fact that he is aged in appearance represents wisdom. One hand points upward, urging believers to always strive for improvement and be mindful of higher powers. The other hand holds a ring, which may represent loyalty and faithfulness. The circle from which the figure emerges can represent the immortality of the soul or the repercussions of our actions, which are brought about by the eternal divine order.
The two wings are composed of three main rows of feathers, representing good thoughts, good words and good deeds, which is the basis of Zoroastrian ethics. The tail is likewise comprised of three rows of feathers, and these represent bad thoughts, bad words and bad deeds, above which every Zoroastrian strives to rise.
The two streamers represent Spenta Mainyu and Angra Mainyu, the spirits of good and evil. Every person must constantly choose between the two, so the figure is facing one and turning his back to the other. The streamers evolved out of earlier symbols sometimes accompanying the winged disk. It some images, the disk has bird talons emerging out of the bottom of the disk. Some Egyptian versions of the disk include two accompanying cobras in the position now occupied by the streamers. (Altreligion.about.com)