The Orders are large groups of mages in Mage: The Awakening, united along philosophical lines (but not always completely by choice). These groups find newly Awakened mages, provide them with mentors, rotes and other resources, then initiates them into the larger Awakened society. The Orders themselves are much like societies; hiding among the people of the Fallen World (i.e. Freemasons) and manipulating things to suit the goals of the Orders. A gathering of the orders is called a Caucus. Mages without allegiance to an Order are referred to as Apostates.
The Pentacle Orders are an alliance between the older Atlantean Diamond and the Council of Free Assemblies. Before the Middle Ages, they were also referred to as the Pentacle, as they were five Orders back then. Two joined with another, establishing four Orders that referred to themselves as the Diamond Precept, the Atlantean Diamond, or simply the Diamond Orders.
The Atlantean Diamond claims philosophical descent from various groups originating in Atlantis, the first city of the Awakened. Though these groups were reorganized during the Exile, they credit Atlantis for giving them their beginning groundwork. These Orders, starting from the Middle Ages, are the Adamantine Arrow, the Guardians of the Veil, the Mysterium and the Silver Ladder.
In addition to the Diamond Orders, another order was created with the birth of the 20th century. A large group of Apostate mages known only as the Nameless battled back the longtime enemies of the Diamond Orders and earned themselves a place at the table of Orders. The Diamond entered an alliance with the Council of Free Assemblies, forming the modern Pentacle Orders.
The Seers of the Throne are another great block of Awakened. The Seers of the Throne are a pyramidical, hierarchical conspiracy divided in multiple Ministries and Tetrarchates that seek to keep the world the way it is, i.e Fallen and humanity in a state of subserviance and helplessness to those in power. They, too, trace themselves back to Atlantis (which prompts some of the more conservative members of the Diamond to try to recruit them as allies, instead of the Free Council). The Throne works to enforce the will of the Exarchs, ascended mages of Atlantean origin that are responsible for the Lie. For this reason, they clash with the Pentacle.
There are multiple smaller Orders without connection to either the Pentacle or the Throne. They are collectively referred to as the "Nameless". These Nameless are often splintered, but some have become quite powerful in their own niches (and are usually declared as Left-Handed).
Mage: The Awakening Orders