Zoroastrianism, (also known as Zarathustraism, Mazdaism and Magianism) is one of the world's oldest monotheistic religions and religious philosophies. It is hard to give an accurate estimate on how many followers there are, and estimates vary greatly from 200,000 from some sources, to 2.6 million in more recent times, the lower number thought to be due to lack of information stemming from the fear of persecution that many Zoroastrians faced, including forced conversions. India has the largest Zoroastrian population due to it's Parsi community, a group of Iranians who fled as refugees in the 10th century to practice their religion freely and ended up settling in Gujarat. Iran has the second highest, with the 2012 census placing the number at 28,000, although the number is thought to be higher, with many Iranians thought to be expressing interest in Zoroastrian art and philosophy, partly as a way of expressing national pride and an identity that existed before the rule of Islam.

Zoroastrianism is based on the teachings of the Persian prophet Zoroaster who was a priest born in ancient Persia 3500 years ago. Little is known about his early life, but what is known has been written into the Gathas, the core of the Avesta, a collection of sacred texts on Zoroastrianism. He was a priest with a wife and children, and opposed how the classes were ruled in his Bronze age society, as well as the many pagan deities that people worshipped. At the age of 30 while bathing as part of a pagan purification rite he had a vision of a shining being, which led him to Ahura Mazda, and five other divine beings. It was the beginning of many visions in which he asked questions, the answers of which formed the foundations of Zoroastrianism. The date that Zoroastrianism was founded is thought to be approximately 1200-1500 BCE due to archaeological evidence and linguistic comparisons to Hindu texts. For 1000 years Zoroastrianism was one of the most powerful religions in the world, and from 600 BCE to 650 BCE it was the official religion of Iran.

Zoroastrian beliefs vary and have changed over the years because of changes and interpretations of the scriptures, the original 'good religion' has only one God; Ahura Mazda (illuminating God) the creator, but later the religion became 'institutionalized' and incorporated some of the earlier Aryan deities as pantheons. A collection of hymns called the 'Gathas' is how Zoroaster left his entire teachings, with his successors later incorporating prayers and guidelines on other aspects of life and interpretations. The Gathas and the later additions (collectively known as the Avesta) introduce a central aspect to the Zoroastrian belief system: Dualism.

Dualism is seen in two separate yet interconnecting ways; cosmic and moral dualism. Cosmic dualism refers to the opposing forces of good (Ahura Mazda) and evil (Angra Mainyu), not the 'devil as one might think in a Christian sense but an opposing, destructive force that saps God's creative energy (Spenta Mainyu) with which he created a pure world. Evil continues to attack God's pure world, causing sickness, famine and aging. Cosmic dualism gives us day and night, life and death and one cannot be understood without the other. Moral dualism is the conflict in the mind of mankind, as God (Ahura Mazda) gave us the freedom to choose which path we take. We can choose truth (asha), the righteous path that ultimately lead to heaven or deceit (druj), the evil with ends with misery and hell. As with cosmic dualism, there are the two opposing forces but moral dualism has a emphasis on choice. When all of mankind chooses Ahura Mazda over the force of evil, Angra Mainyu, paradise on earth will be realized. Modern Zoroastrians are optimistic with their outlook, believing mankind to be ultimately good and that it will eventually triumph over evil. These thoughts on heaven and hell are thought to have heavily influenced future religious beliefs like Islam and Judaism.

Zoroastrians try to live their lives by the maxim 'good thoughts, good words, good deeds' and at the age of seven are given a sudreh and kusti (shirt and cord) as part of an initiation ceremony, tying the cord around themselves three times to remind them of this. They go on to perform this ritual several times a day with prayers. These prayers are done facing the sun, fire or other source of light, which symbolizes purity, another belief central to Zoroastrianism. Sacred fires are maintained in their places of worship, the fire temples and represent the illuminated mind, as well as the light of God. Family and community are central to Zoroastrian belief, as Zoroaster himself was a family man and most worship happens within the family home. They are active in their communities, often donating generously to social or educational initiatives and the Parsi community in India is known for it's large contributions to Indian society. Individuals are considered equal, men, women, rich and poor, and can only best one another by their positive choices. Some see Zoroastrianism as the first 'ecological' religion, as their emphasis on purity means they pay special attention to not corrupting the atmosphere, rivers and land. Many Zoroastrians cover their head to remind themselves of their spirituality, although this is not a requirement.

Zoroastrianism is a faith full of holy days, fasts and festivals and many, like the six Gahanbars correlate closely to nature. The Zoroastrian calendar varies, partly because of numerous changes over the centuries among the different communities, whose differing beliefs could see them viewed as sects; the Parsis of India, the Qadimis of Iran and the Faslis, with the Parsis further split into sects, a few of which are considered occult.

Zoroastrian business owners often have a good reputation of being fair to work with. This is because their of way of life revolves around the six ideals of a good mind, principled living, independence, serenity, wholeness and an undying spirit. A quote from the Avesta that seems to encapsulate the Zoroastrian way is "Happiness comes to them who bring happiness to others."