US Civil Procedure/Introduction
Most law school students learn the Federal Rules of Civil Procedure which have been adopted in their entirety by many States, although a significant number US states (including California, New York and Pennsylvania) have distinctively different Rules of Civil Procedure. Even if the text of the Federal Rules of Civil Procedure is not adopted in its entirety by a state, the state may end up using the same numbering system. Even though the Federal Rules allow lawyers to easily adapt to practice in new jurisdictions, it is important to read the local rules of civil procedure.
Most law schools teach civil procedure by teaching the concept of jurisdiction before teaching the technical rules.
Wikibooks asks for discussion of this topic, but there really isn't much to discuss. Civil Procedure, or CivPro as it's known to law students, simply describes the process by which civil (not criminal, that's a different set of rules) cases are brought into the court system and how they are handled procedurally once they are in the system. CivPro gives detailed rules for such issues as how to start a law case, what sort of notice you must give to the other party and how, how to tell the judge that you want him or her to do something, what information you are entitled to get from the other party or parties and how to do it (the process called discovery), how to conduct civil trials, and the like.
A civil case is one in which one party or group of parties, usually not the government, sues another party or group of parties claiming they did or were about to do something wrong. The wrongs sued about are generally in three categories: tort, contract, and other.
Contract actions are, as the term suggests, about enforcing (or not enforcing) contracts. Often these are written contracts, but oral contracts are perfectly legal and enforceable IF the court can decide exactly what the terms agreed on were: the problem with oral contracts is not whether they are enforceable, but what the actual contract was, since usually party A says one thing and party B says another.
Tort actions seek redress for some wrong done by another person (legally a person includes corporations, governments, etc.) Tort claims can range widely, from suing over damages from a dog bite, to auto accidents, to a branch from your tree falling on my roof, to your borrowing my lawnmower and not returning it. Almost any civil harm you can think of, including asking the court to award you millions of dollars because a business temporarily lost a pair of your pants. Don't laugh, it happened.
The civil courts also deal with many sorts of cases which are neither contract nor tort. The list is almost endless, but it includes such things as divorces, paternity cases, landlord-tenant disputes, probate (estate settlement, guardianship and conservatorship issues), ordering a parent to allow a child to undergo necessary medical treatment which the parent is resisting, injunctions (asking the court to order someone to stop doing something they are doing or not to do something they plan to do), and on and on.
Basically, any action that isn't the government bringing criminal charges against a person is a civil action.
The Rules of Civil Procedure, by the way, are only one of the sets of rules that govern the practice of law. Most states in the U.S. (maybe all except Louisiana) have numerous sets of rules which govern, for example, their criminal, their appellate courts, and their business operations, with general rules applicable to all situations, and many other collections of rules. And most local courts even have their own sets of rules which supplement state rules.