# Why do I need to use \paragraph{} after a \section{} to get correct indenting whereas a blank line suffices for subsequent paragraphs?

I have noticed that whenever I start a new section, subsection, etc., I need to preface my text block with \paragraph{} to get correct indentation for the first paragraph. In subsequent paragraphs, however, I note that I can simply leave an empty line and the paragraph is formatted correctly.

Is this correct behaviour, and if so what is the reason for this? Is the first paragraph supposed to be naturally unindented, perhaps for the reason of compatibility with lettrines and such? Is there an easier (terser) way to stipulate first-paragraph indentation?

I'm using the article documentclass under xelatex.

Thanks for any insight you can offer.

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P.S. Do not do this! –  Will Robertson Sep 2 '10 at 23:57
Do not do what? –  Richard Terrett Sep 3 '10 at 7:47
Do not use `\paragraph{}` for formatting purposes. Ever! –  Will Robertson Sep 8 '10 at 10:04
–  Qrrbrbirlbel Jun 7 at 22:22

This is the expected behavior. If you look into any book, you will see that the first paragraph of each chapter/section is not indented. The indentation is there to signify the start of a new paragraph and thus is not necessary for the first paragraph.

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Thanks for this clarification. The rationale certainly makes sense, however not all texts follow this indenting pattern - I'm looking at a paper from geochim. cosmochim. acta which does indent first paragraphs after sections. –  Richard Terrett Sep 1 '10 at 9:51
@eutactic: Unfortunately, some journals and the like have poor style requirements which they keep for the sake of uniformity. ACM conference style, for example, is simply awful. –  TH. Sep 1 '10 at 10:04
Does not this rule depend on the selected language? I think that in French, the first paragraph is indented. –  pluton Mar 10 '11 at 13:11
@pluton Yes the french option to babel changes that (and some other global things too—see the documentation). –  Caramdir Mar 10 '11 at 17:00

It is correct behaviour and the reason is that you don't need to show with an indent that a paragraph starts here as everyone knows that after a section title a new paragraph starts. You can change this with indentfirst package.

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That package is very handy, thankyou. This said, in reference to what you and Caramdir have said regarding standard conventions, it may also be extraneous. –  Richard Terrett Sep 1 '10 at 9:54
@eutactic: Well, the ACM might find it useful ;-P –  SamB Nov 23 '10 at 18:00

What perhaps isn't obvious from the other answers is that `\paragraph{}` is a part of the sectioning hierarchy, coming between `\subsubsection{}` and `\subparagraph{}`.

With the right levels of `{tocdepth}` and `{secnumdepth}`, you can even make it appear in the TOC with a lunatic prefix like 1.3.1.1.

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Actually, though what people say here is correct, I will add that there is an argument over indentation when there is a space between paragraphs. Both the space and the indentation are, plainly, to alert the reader that a new paragraph is starting. But there is no need for both alerts. The indentation is correct when there is no space between paragraphs, but it's not as absolutely correct if there is a large enough space to clearly indicate a new paragraph. Many publishers today are choosing the space over the indentation.

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You are correct about people choosing the space over the indentation. This is very common, especially for screen reading. I thought of an in-between solution and came up with this question tex.stackexchange.com/questions/2650/… so far it it has defeated me, as I do not want to mess with output routines! –  Yiannis Lazarides Nov 26 '10 at 11:14
@Yiannis - To be honest, I don't mind the look of using a space instead of indent. To me it makes the page look less cluttered and more symmetrical (yes, I'm a little OCD, what can I say?). Having confessed that I have to say that I liked your question as it presents me with an opportunity to learn more about TeX's digestive tract. In the TeXbook Knuth uses the metaphor of the TeX processing strategy as having 'eyes, mouth, and stomach.' In a later section he talks of two parts of the stomach's digestive process. So, I thought that by the time the token stream reached the cont--> –  bev Nov 27 '10 at 0:03
-->cont 2nd digestive stage there was no more conditional, calculations, or decisions about the layout, i.e. all the float placements are done. In fact I thought that the float placements take place either in the mouth, where the conditionals are filtered, or in the first part of the stomach. To be more specific, when TeX is processing the 'current page' which has all the candidate material, including floats, one of the things that it is doing is playing with spaces and glue to make things look right. It seems to me that while it is mucking about with spaces and glue cont--> –  bev Nov 27 '10 at 0:21
-->cont it could decide to make `\parindent0pt` for the subsequent paragraph. I don't see why, as Will Robertson said (in your question), TeX would have to go back and do something to redo an already finished page. –  bev Nov 27 '10 at 0:24
Thanks for volunteering to solve the problem! Need to read the book again! –  Yiannis Lazarides Nov 27 '10 at 8:46