Unlike criminal cases where the state acts as the prosecutor on behalf of society, civil cases involve disputes between individuals, groups of individuals, or organizations (e.g., companies, governmental organizations). When a person or entity 'sues', they file a lawsuit. 'Litigation' is this act of taking legal action.
The American civil law system is one of the most expansive in the world. There are 4 lawyers and 24 lawsuits filed for every 1000 people in America, compared to 2 lawyers and 5 lawsuits for every 1000 people in Germany, and 0.3 lawyers and 1 lawsuit for every 1000 people in Japan.