A constitutional republic is a type of government in which the officials are elected by the people. The republic must govern according to the laws of the constitution, and its actions are subject to judicial review. Although many people consider it a democracy, the United States is actually a constitutional republic.
The major difference between a constitutional republic and a democracy is that in a democracy, all laws and legislation are decided by a popular vote, and in a constitutional republic, the elected officials decide on legislation as representatives of the people.
In addition to having elected officials, the other primary defining factor of a constitutional republic is a well-defined constitution that limits the power of the government and elected officials and also sets out basic structures, laws and procedures under which the country is to be governed. The constitution must also explicitly specify the rights of the people and is intended to be followed precisely as the people who framed it intended. All legislation is also subject to judicial review, which can void any laws that are not in line with the constitution.
In this type of government, the officials are also subject to review, and they can be removed from their positions if they do anything illegal or fail to live up to their duties as specified under the constitution.