Pleading is the exchange of written claims and defenses between and among the litigants.
Technically, the pleadings include only the complaint and the answer. In some jurisdictions pleadings also include a reply to the answer. The proper common law writ depended upon how technically correct the claim was alleged. Many good claims were dismissed not on their merits but because of procedural hyper-technicalities. Common law pleadings were used and evolved over 675 years between 1200 and 1875.