In modern politics, a state is an association which has control over a geographic area or territory. States are seen as having three main pieces:
A territory
A people
Some institutions (which have the power to make rules).
There are different forms of government a state can have, for example a republic or a monarchy. Sometimes states form their own countries. At other times many states work together to form a country (like the United States). Most states also have armed forces, civil service, law and police.
The earliest states were just groups of power. A group of farms working together or a group of factories working together could be 'states' since people can control them and protect them.
More organized states could be the monarchies such as early Egypt under the Pharaoh. Following this were larger more military-based states such as the Roman Empire. The most important early states, however, were the Ancient Greek states which had freedom, writing and a democracy.

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