The Major Arcana is made of 22 cards, and it demonstrates to the seeker the nature of their spiritual path. The more major arcana that show in a layout for example - the greater the opportunity for the seeker to develop and understand firstly themselves and how they interact with the world and society on a "bigger picture" and then secondly, where they may be on their "spiritual path and journey". My personal preference for a tarot deck is that of the Universal Waite, or Ryder Waite. I find that they "speak absolute volumes" in the artwork alone. The purpose of the tarot is to draw to you your own innate sense of wisdom and to empower you within your day to day life. This is probably the reason why the tarot became so unpopular through out history, and why "witchcraft" became taboo. Prior to these times they were known as the healers and "seers" and had a greater level of respect by society.
History doesn't define clearly when the tarot was first created as a tool of empowerment however, it does showt that the Knights Templar were created about 1143AD, and the first inquisitions by the Catholic Church in circa 1184 AD (40 years later). Given that the Knights Templar are said by some to be founders of the "Rosencrucians", who beleived that Mary Magadalene was the wife of JEsus Christ and that he didn't die on the cross and was instead transported to France where he and Mary "lived happily ever after having a tribe of children that ended up as reigning monarchs around the world", it would be fair to say that the tarot surfaced somewhere around this time.
There is much debate over when the cards originated and from where. Som epeople believe that hey have derived from Ancient Hieroglyphics of the Egyptians, while yet others believe that they originated in China. Yet others have pointed out that there are 22 numbers in the major arcana which refer to the 22 letters of the Hebrew alphabet that carry spiritual and mystical connotations. Then there are others that say that they derived from ancient astrologers.
There is also a suggestion by some that the High Preistess in the pack refers to Mary Magdalene, and the Magician is demonstrative of Jesus Christ. This is possible - each religion has founded its own divinatory mehtod and mechanism to 'obtain and access Divine Guidance". For Islam it is the Kabbalah as an example.
The reality is - it doesn't really matter what the history of the deck is.. it is the way the tool is used today in the present. It provides us with insight into what is going on, at a subconsious level and what is availble to us by drawing up on the "Superconscious", through drawing upon the wisdom of the deck and the divine. The current decks are modelled on associations by the Hermetic Order of the Golden Dawn, with a list of associations that are recognised on this site. here.
I use two seperate decks -that of the Hermetic Tarot which "speaks" in symbolism and then the Universal Waite, which draws upon mulitple metaphysical properties to convey the messages, in the form of symbolism and colour, and the actual pictures. The Rider Waite also ties in with my own "story of the tarot", and a person does not need to be a psychic to understand the meanings of the cards, if they are able to "draw and feel" the pictures. Each picture tells its own story also.
When the major arcana appear in a reading layout - they signify amjor events or decisions that could relate to a practical matter, spiritual or emotional. They point to influential changes occuring in our lives, and the way the cards land indicates the nature of the influence and whether it will bode positive or negative. (Personally I am not fond of the words positive or negative - the influences will either lead to greater joy and peace of mind, or they show a possibly more turbulent path).