What is an introduction or preface to a literary piece known as?

An introduction or preface to a literary piece is known as a prologue.

Here are some other terms that might be used depending on the specific type of introduction:

* Foreword: Written by someone other than the author, often an expert or someone who knows the author well.

* Preface: Written by the author themselves, explaining their purpose and intentions for writing the piece.

* Introduction: A brief overview of the subject matter and key themes of the piece.

While these terms may be used interchangeably, they often carry specific connotations.