What's the purpose of paragraph first-line indentation and where is it used?

Question

I've asked a typesetter and she didn't even know about first line indentation on subsequent paragraphs.

Neither did I ever encounter it in "real" life but have to struggle with it's removal every other time when facing latex tasks.

Where in western Europe is it usually used?

https://www.overleaf.com/learn/latex/Paragraphs_and_new_lines#Paragraph_indentation

Answer 1

There are publications that indicate paragraphs by leaving some extra space between them (most often with ragged right typesetting) but I would claim that they are in the minority if you go into a library and open books at random, so I'm a bit surprised you state you have never encountered them in "real" life".

Perhaps your background is CJK scripts in which case the situation is probably different.

The most common approach in "western" typography (which is where TeX originate) is to typeset text justified and (last not least to save space) not to put extra white space between paragraphs. If you do this, then you have the issue that the last line of a paragraph can become completely filled once in a while. To be able to nevertheless always enable the reader to see that a new paragraph has started the first line therefore typically indented by a small amount (and since after a heading this visual clue is unnecessary it is normally left out). That's about the background.

But there is no reason to "struggle" with it. If you do prefer a different style, LaTeX actually makes it easy for you to adjust your documents to any style and there is no need to go \noindent on every paragraph as you might have feared from the description on overleaf (that just describes how to turn it off for individual paragraphs which is sometimes useful. Instead use a package such as parskip or a class that sets up the style you prefer automatically.

Answer 2

It is the common practice in Western European and English language documents.

Robert Bringhurst in his The Elements of Typographic Style, Hartley & Marks, 1999 (or later), the typographer's bible, says:

2.3.1 Set opening paragraphs flush left.

2.3.2 In continuous text, mark all paragraphs after the first with an indent of at least one en.

Another way of indicating a paragraph is to have no indentation but to precede it with a blank line; this of course can be problematic if the breaks between paragraphs coincide with page breaks.

Answer 3

Here are my two cents :).

• Normally, a text reflects the structure of the idea/content/thoughts that is described.
• Therefore, a text is divided into several logical units.
• Examples for such logical units are parts, chapters, sections, [...], paragraphs, and sentences.
• Main point: There are several ways to reflect this logical structure visually. So the answer to the first part of your question ("What's the purpose of paragraph first-line indentation [...]") is that the purpose is to visually highlight the logical structure of the text (division into paragraphs).
• In the case of paragraphs, one typically uses vertical whitespace between paragraphs (parskip) OR indent the first line of a paragraph (parindent).
• Below, I attached an excerpt of the famous book "The Elements of Style". The book seems to be famous among LaTeX users/experts, see also Peter Wilson's great answer.

Remarks: This screenshot was taken from the ebook, Kindle Cloud Reader, version of the book. The point I tried to - and failed - to make was the written content of the screenshot and not how it looks. The content describes that a paragraph is an important concept of written language etc.

PS: In my personal experience, in German engineering, using parskip is more common than parindent (as pointed out by Frank in his comment, this may be a result of using MS Word). I attached a screenshot of my PhD thesis. But the idea is the same: Each paragraph is about one thought/topic/logical unit. parskip or parindent are just a way to communicate the beginning/end of paragraphs so that the reader understands better the logical structure.

Answer 4

It's actually quite common. I see it in German books all the time (and almost certainly not just there). Consider this image from Tschichold’s seminal work »Erfreuliche Drucksachen durch gute Typographie«:

It's simply a space-saving alternative to having more vertical space.

Answer 5

I somewhat disagree with the purposes given so far, namely that this is to visually mark paragraphs.

While having such a visual distinction is a consequence of the indentation, it is not the purpose. Not justifying the last line would suffice for this (assuming justified text). The ambiguity in the rare case of a full last line can be avoided in historical manual typesetting by just slightly adjusting the justification gap in the paragraph or adding a respective penalty in to the TeX linebreaking algorithm. If it was only for this ambiguity, historical typesetters wouldn’t have introduced the indenting convention.

The main benefit of indenting paragraphs is that it gives the reader some visual reference points on the left side of the text which they can use when jumping from the end of one line to the beginning of the next. Without the indent, you have just a homogeneous wall of text and it happens more easily that you accidentally skip a line or read the same line twice.

There is no need for this at the beginning of a section (or similar), hence indenting is usually not used there. Also if paragraphs are spaced, this already provides visual reference points and obviates the need for indenting.

As for the popularity, everything I have ever encountered had either:

• indented paragraphs,
• vertically spaced paragraphs,
• no paragraphs at all (e.g., a brochure),
• strong typography and design flaws (overly long lines, bad colour contrast, inappropriate typeface), i.e., it was probably not professionally typeset.

And I am the kind of person who notices such things. (I read mostly German and English material.)