What do you call a note that gives preliminary information before the main part?

Question

I'm looking for a single word (if not, a natural phrase) for a note that you write before starting the main article/part/question etc.

It can give preliminary information (in general). However, it can be a mild warning (but I would like to avoid calling it a "warning" which is too strong) or a reminder (thus, we can call it a "reminder" but I want a more general word).

An example context would be, when you are posting a question on stackexchange sites, you put a note in advance that people read it before the question and you make them think twice before posting an answer, you remind them that the question is (not) about this or that etc.

For example:

_____: This question is not only about finding a single word. I would like to get a detailed answer that addresses all the related questions.

<< Main question... >>

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I considered the word note itself but I want to distinguish it from the notes that you write after or during the main part.

Then, advance note¹ came to my mind as a phrase but it also has another meaning and can be confused with advance notice.

Prenote² could be a nice word but it does not sound that natural and dictionaries list it as a verb only.

There are of course words like preface and prologue but they are usually too formal and comes before longer written works like novels.

Caveat³ is similar to warning but it might give special instructions. Can it be the word I'm looking for? I might have seen it used in this way on EL&U but it is used in law also.

_{I might be over-thinking and the answer might be very simple but I wanted to give as much information as I can. You might also talk about differences between words that fit to similar settings.}

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_{¹ a draft on owners or agents of a ship drawn by the master for the benefit of a sailor usually for one month's advance wages [MW]}

_{² trans. To note or mention previously. [OED]}

_{³ an explanation or warning that should be remembered when you are doing or thinking about something [MW]}

Answer 1

A suitable word for your brief introduction is preamble. It's not as formal as preface, and can be as short as a sentence (which would be unusual for a preface). Preamble can be countable or a mass noun, as Oxford Dictionaries shows:

1. A preliminary or preparatory statement; an introduction:
   he could tell that what she said was by way of a preamble
   I gave him the bad news without preamble

ODO

It's pronounced as three syllables, and does have the same root as amble — medieval Latin praeambulum, from late Latin praeambulus 'going before'.

Answer 2

I'd usually use Preface in this sense, and I'd argue it's most common.

There's also Precis, though I think that it's more commonly used to describe a sort of brief preliminary synopsis.

Answer 3

NB: Maybe something might be interesting to note well.

Answer 4

If we forget about Stack Exchange (for a moment) and everything after the first two paragraphs, abstract fits nicely.

Abstract (summary) -Wikipedia

An abstract is a brief summary of a research article, thesis, review, conference proceeding or any in-depth analysis of a particular subject or discipline, and is often used to help the reader quickly ascertain the paper's purpose. When used, an abstract always appears at the beginning of a manuscript or typescript, acting as the point-of-entry for any given academic paper or patent application.

Answer 5

Preempt
pre·empt, prēˈempt/ verb

1. take action in order to prevent (an anticipated event) from happening; forestall

2. acquire or appropriate (something) in advance -Google

A preamble is simply something said before hand. A preemption offers an introductory caveat. Also, prompt might fit where appropriate.

Answer 6

A very well-known word that has this meaning is “introduction”.

TFD gives:

1. The act or process of introducing or the state of being introduced.
2. A means, such as a personal letter, of presenting one person to another.
3. Something recently introduced; an innovation: "He loathed a fork; it is a modern introduction which has still scarcely reached common people" (D.H. Lawrence).
4. Something spoken, written, or otherwise presented in beginning or introducing something, especially: a. A preface, as to a book. b. Music A short preliminary passage in a larger movement or work. c. A basic introductory text or course of study.