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A rules book for a state is called the constitution. It sets all basics and fundamental principles by which the state is governed. It explains the main institutions of the state and set the relationship between these institutions. It describes limits on the exercise of power and also describes the rights and duties of citizens.
The rule book is codified in a single document, known as a codified (or written) constitution in almost all countries but the UK. Written or codifies constitutions are produced following a revolution (like the American constitution of 1787 or the French constitution of 1791 and the Pakistan constitution of 1972); total defeat in war (like the post-war constitutions of Japan and Germany); or a complete collapse of legitimacy of the previous system of government (like post-Soviet Russia or post-apartheid South Africa); or the attainment of independence (like all the countries of the former British empire). These things have happened to the United Kingdom because the UK never had cause to codify its constitution. (Our one revolution, in the 17th century, did briefly produce a written constitution: Cromwell’s Instrument of Government).
Written or codified constitutions contain fundamental, superior laws, and are harder to amend than unwritten constitutions. Change in constitutions approves by a super-majority in the legislature, a referendum, or sometimes both. For example, an amendment to the Pakistani constitution requires approval by a super-majority of two-thirds. Amendment to the US constitution requires a two-thirds vote in both Houses of Congress so the written constitution is very difficult to change or amend.
Change in the rule book or constitution can also be achieved by interpretation or re-interpretation of the constitutional text by the supreme courts. Because of the high threshold required to amend the constitution, in some countries (such as the US) judicial decisions can be as important in revising the constitution as the process of formal amendment.
The Parliament of a country passes a constitution. A constitution describes the rules of our political system. It describes and protects the fundamental rights of the people of the country. It describes the institution, the powers of institutions, and how they use the powers under the constitution.