Holy Order of the Jedi Knights
Grand Master- Also known as Master of the Order, the Grand Master is the head of the High Council and generally regarded as the most powerful and wise Master of the Order. He is chief liason between the Order and the Republic.
Jedi Councilor- Not a rank exactly, but more a title held by those that are part of the various Jedi Councils that exist. This includes the Jedi High Council, as well as the Council of First Knowledge, Council of Reconciliation, Council of Reassignment, as well as the various Academy Councils.
Jedi Master- The second highest rank a Jedi could obtain, and a traditional requirement for becoming part of the Jedi Council, the main interface between the Jedi and the government of the Republic. It is reserved for those who have shown exceptional devotion and skill as well as balance in the Force and often combat.
Jedi Knight- The rank to which Jedi reach when they complete the Jedi Trials as Padawans, it is the most commonly associated rank with the Order. Typically taking ten to twelve years as a Padawan to achieve, they are the backbone of the Order, and at this point can take on a Padawan of their own, whom often call them Master. They take on the majority of the missions the Order undertakes, with the help of their apprentice if they have one, and if the Padawan is ready.
Jedi Padawan- A child, or in some cases an adult, who begins serious training under a Jedi Knight or a Jedi Master, chosen by the Knight or Master him/herself from the ranks of the Younglings. They are typically chosen between the ages of eight and ten, but sometimes as early as six.
Jedi Initiate- Otherwise known as Youngling, they are Force-Sensitive children undergoing basic training as Jedi. If they are not chosen as a Padawan by the age of thirteen, they are given another assignment within the Order and cease their training.