Civil procedure is the written set of rules that sets out the process that courts will follow when hearing cases of a civil nature (a "civil action"). These rules explain how a lawsuit must be commenced, what kind of service of process is required, the types of pleadings, motions, and orders allowed in civil cases, the timing and manner of depositions and discovery, the conduct of trials, the process for judgment, various available remedies, and how the courts and clerks must function.
The United States federal court system adopted the Federal Rules of Civil Procedure on September 16, 1938 before which time there were varying rules that governed different types of civil cases such as cases at law or in equity or in admiralty. There are exceptions to the types of cases that these rules now control but they are few in number and somewhat esoteric (e.g., "prize proceedings in admiralty"). Most states have also adopted the Federal Rules (with various minor modifications) to govern procedures in their state court systems.
California is the odd exception in that its homegrown civil procedure system is enshrined in statutory law (the Code of Civil Procedure), not in rules promulgated by the state supreme court or the state bar association.
Alternative dispute resolution proceedings and administrative law proceedings both tend to have relatively simple rules of procedure, in comparison to the highly formalized procedures seen in the federal and state courts.
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