Parliamentary procedure is the accepted rules, ethics, and customs governing meetings of an assembly or organization. It is supposed to represent the will of the majority. Its object is to allow deliberation upon questions of interest to the organization and to arrive at the sense or the will of the assembly upon these questions. Self-governing organizations follow parliamentary procedure to debate and reach group decisions--usually by vote--with the least possible friction.
In the United Kingdom, Canada, Ireland, Australia, New Zealand, South Africa and other English-speaking countries it is often called chairmanship, chairing, the law of meetings, procedure at meetings or the conduct of meetings. In the United States, parliamentary procedure is also referred to as parliamentary law, parliamentary practice, legislative procedure or rules of order.
Rules of order consist of rules written by the body itself (often referred to as bylaws), but also usually supplemented by a published parliamentary authority adopted by the body. Typically, national, state/provincial and other full-scale legislative assemblies have extensive internally written rules of order, whereas non-legislative bodies write and adopt a limited set of specific rules as the need arises.
In the 16th and 17th century, there were rules of order in the early parliaments of England. In the 1560s Sir Thomas Smyth began the process of writing down accepted procedures and published a book about them for the House of Commons in 1583. Early rules included
In Canada, for example, the House of Commons uses House of Commons Procedure and Practice as its primary procedural authority. Others include Arthur Beauchesne's Parliamentary Rules and Forms of the House of Commons of Canada, Sir John George Bourinot's Parliamentary Procedure and Practice in the Dominion of Canada, and Erskine May's The Law, Privileges, Proceedings and Usage of Parliament from Britain.
The rules of the United States Congress were developed from the parliamentary procedures used in Britain. The American parliamentary procedures are followed in many nations, including Indonesia, the Philippines, Mexico and South Korea.
The procedures of the Diet of Japan have moved away from the British parliamentary model. In Occupied Japan, there were efforts to bring Japanese parliamentary procedures more in line with American congressional practices. In Japan, informal negotiations are more important than formal procedures.
Written codes of rules govern in Italy the life of the Houses of the Parliament: the Constitutional Court is judge on the limits beyond which these regulations cannot go, exceeding the parliamentary or political function (judgement n. 120 of 2014), and on their bad application when a law is passed through.
Parliamentary procedure is based on the principles of allowing the majority to make decisions effectively and efficiently (majority rule), while ensuring fairness towards the minority and giving each member or delegate the right to voice an opinion. Voting determines the will of the assembly. While each assembly may create their own set of rules, these sets tend to be more alike than different. A common practice is to adopt a standard reference book on parliamentary procedure and modify it through special rules of order that supersede the adopted authority.
A parliamentary structure conducts business through motions, which cause actions. Members bring business before the assembly by introducing main motions, or dispose of this business through subsidiary motions and incidental motions. Parliamentary procedure also allows for rules in regards to nomination, voting, disciplinary action, appeals, dues, and the drafting of organization charters, constitutions, and bylaws.
The most common procedural authority in use in the United States is Robert's Rules of Order. Other authorities include The Standard Code of Parliamentary Procedure (used by some medical and library organizations)  and Demeter's Manual of Parliamentary Law and Procedure.
In English-speaking Canada, popular authorities include Kerr & King's Procedures for Meeting and Organizations. The Conservative Party of Canada uses Wainberg's Society meetings including rules of order to run its internal affairs.
Legislative assemblies in all countries, because of their nature, tend to have a specialized set of rules that differ from parliamentary procedure used by clubs and organizations.
In the United Kingdom, Thomas Erskine May's Treatise on the Law, Privileges, Proceedings and Usage of Parliament (often referred to simply as Erskine May) is the accepted authority on the powers and procedures of the Westminster parliament. There are also the Standing Orders for each House.
Of the 99 state legislative chambers in the United States (two for each state except Nebraska, which has a unicameral legislature), Mason's Manual of Legislative Procedure governs parliamentary procedures in 70; Jefferson's Manual governs 13, and Robert's Rules of Order governs four. The United States Senate follows the Standing Rules of the United States Senate, while the United States House of Representatives follows Jefferson's Manual.
Mason's Manual, originally written by constitutional scholar and former California Senate staff member Paul Mason in 1935, and since his death revised and published by the National Conference of State Legislatures (NCSL), governs legislative procedures in instances where the state constitution, state statutes, and the chamber's rules are silent.
According to the NCSL, one of the many reasons that most state legislatures use Mason's Manual instead of Robert's Rules of Order is that Robert's Rules applies best to private organizations and civic groups that do not meet in daily public sessions. Mason's Manual, however, is geared specifically toward state legislative bodies.
In the United States, individuals who are proficient in parliamentary procedure are called parliamentarians (in other English-speaking countries with parliamentary forms of government, "parliamentarian" refers to a member of Parliament).
Several organizations offer certification programs for parliamentarians, including the National Association of Parliamentarians and American Institute of Parliamentarians. Agriculture teachers who coach teams in the National FFA Organization (formerly Future Farmers of America) parliamentary procedure contest can earn the title Accredited Parliamentarian (AP). Parliamentarians perform an important role in many meetings, including counseling organizations on parliamentary law, holding elections, or writing amendments to the constitution and bylaws of an organization.
Since approximately 95% of the organizations in the U.S. prescribe Robert's as their parliamentary authority, the 11th edition is most likely the parliamentary authority for all organizations you are involved in.