From Catherwood v Thompson 1958 OR 326 (Canada), a trial was stated to be an:
"... investigation and determination of a matter in issue between parties before a competent tribunal, advancing through progressive stages from its submission to the Court or jury to the pronouncement of judgment.
"When a trial may be said actually to have commenced is often a difficult question but, generally speaking, this stage is reached when all preliminary questions have been determined and the jury, or a Judge in a non-jury trial, enter upon the hearing and examination of the facts for the purpose of determining the questions in controversy in the litigation."
In the 2000 edition of Roger Salhany's book, Preparation and Presentation of a Civil Action (ISBN 0-433-42412-5), the retired Ontario judge aptly summarized the process at page 68:
"The purpose of any trial should be the discovery of the truth. In Canada, the mechanism for that discovery is the adversary system, a method of trial unique to those countries whose legal institutions stem from the English common law....
"Through examination-in-chief by counsel for the party that calls the witness and cross-examination by counsel for the opposing side, the accuracy or reliability and honesty of the testimony of the witness is tested for its truth. The courtroom becomes the only laboratory in which the trier of fact is able to make a determination of the truth."
The process leading to a trial and, indeed, its parameters, as trial judges find themselves reminding inexperienced trial lawyers, requires pleadings, usually both of a statement of claim or statement of defence.
For some history on trial, see trial by battle and trial by ordeal.