The prologue
Usually it is considered a prologue.
prologue
exposition
The introductory piece of music for a long composition is usually called the "overture."
The introductory music is called the overture.
Introductory Federalist Member
No, it is not a concerto as the orchestra part only plays an introductory fanfare and a miniscule part in the centre of the piece. Furthermore Chopin arranged this piece as a piano solo. A concerto is based on movements and this piece certainly has no movements.
Les Miserables
The introductory paragraph of Ellis' novel sets the tone for much of the remaining story.
The answer is the preface. A prologue is the introductory or prefatory section of a novel.
The introductory piece of music for a long composition is usually called the "overture."
It is the introductory part known as Preamble
the preamble
Setting
D. G. Bobrow has written: 'Introductory calculus' 'Supplement for introductory calculus Part 1'
It is a part at the start of the mass, to do with all the blessings and things like that.
The introductory music is called the overture.
A unit of a novel is called a chapter.
A novel written as letters (epistles) is called an epistolary novel.
EpilogueAnother answer:An "epilogue," by definition, is "a concluding part added to a literary work, as a novel;" thus an epilogue comes last. (A "monologue" is "a presentation by a single performer," [mono = one] without regard to placement.)Is it possible you meant to compare "epilogue" with "prologue?" (A "prologue" is "a preliminary discourse; an introductory speech; any introductory proceeding," so it, by definition, comes first.)