An Islamic state (Arabic: الدولة الإسلامية, al-dawla al-islamiyya) is a type of government, in which the primary basis for government is Islamic religious law. From the early years of Islam, numerous governments have been founded as "Islamic", beginning most notably with the Caliphate established by Mohammad himself and including subsequent governments ruled under the direction of a caliph (meaning, "successor" to the prophet Mohammad).

However, the term "Islamic state" has taken on a more specific modern connotation since the 20th century. The concept of the modern Islamic state has been articulated and promoted by ideologues such as Abul Ala Maududi, Ayatollah Ruhallah Khomeini, and Sayyid Qutb. Like the earlier notion of the caliphate, the modern Islamic state is rooted in Islamic law. It is modeled after the rule of Mohammad. However, unlike caliph-led governments which were imperial despotisms or monarchies (Arabic: "mulk"), a modern Islamic state can incorporate modern political institutions such as elections, parliamentary rule, judicial review, and popular sovereignty.

State commonly refers to either the present condition of a system or entity, or to a governed entity (such as a country) or sub-entity (such as a province or region).

In geometric measurements, length most commonly refers to the longest dimension of an object.

In certain contexts, the term "length" is reserved for a certain dimension of an object along which the length is measured. For example it is possible to cut a length of a wire which is shorter than wire thickness. Another example is FET transistors, in which the channel width may be larger than channel length.

Length may be distinguished from height, which is vertical extent, and width or breadth, which are the distance from side to side, measuring across the object at right angles to the length.

Length is a measure of one dimension, whereas area is a measure of two dimensions (length squared) and volume is a measure of three dimensions (length cubed). In most systems of measurement, the unit of length is a fundamental unit, from which other units are defined.

Measurement has been important ever since man settled from his nomadic lifestyle and started using building materials; occupying land and trading with his neighbours. As society has become more technologically oriented much higher accuracies of measurement are required in an increasingly diverse set of fields, from micro-electronics to interplanetary ranging.