Correct use of \paragraph titles?

Question

How should I use \paragraph? I mean, If I want to put "Characteristics", should I put \paragraph{Characteristics} or \paragraph{Characteristics:}. Or is it up to me which one to use?

Answer 1

I think a colon would look bad, but a period looks good. Not having it can look strange since you end up with something like

Title    Another word starting with a capital letter.

as opposed to

Title.   The start of a thought.

The "Title Another" looks odd to me.

Answer 2

In the standard classes, a horizontal space of 1em will separate the paragraph title and the following text; therefore there's no need for ending the title with a colon. Of course, this is no "hard-and-fast"-rule - a colon would be more out of place at the end of a section title (which is by default vertically separated from the following text).

EDIT: In response to TH.'s answer: I'll endorse a period at the end of a paragraph title provided that the space after it is reduced to a normal word space. A period plus a gap of 1em looks like overkill to me (but then, I'm a fan of \frenchspacing.)

Answer 3

Automatically place a period at the end of paragraph titles

I just solved my own question (from the comment). Put this into the preamble:

\let\originalparagraph\paragraph
\renewcommand{\paragraph}[2][.]{\originalparagraph{#2#1}}

If you don't want a period, you can use something like \paragraph[?]{Title}, then a '?' will be placed at the end instead of a period.

Warning: I'm not sure if this is an ugly soliton (there might be problems with the TOC for example). Edits of this answer are welcome... :)

Minimal example

\documentclass{scrbook}

    \let\originalparagraph\paragraph
    \renewcommand{\paragraph}[2][.]{\originalparagraph{#2#1}}

\begin{document}

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nullam auctor vulputate massa. Cras eu arcu non nisl tempor rhoncus. Sed tortor ipsum, molestie non gravida ut, tempor quis lacus. Sed quis nisi sit amet nibh elementum bibendum quis ut erat. 

\paragraph{Lorem}
Nulla facilisi. Cras et diam massa. Suspendisse congue leo at nunc ultrices cursus. Cum sociis natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Donec sed scelerisque odio. Morbi ac neque erat, id porta turpis. Donec mollis velit ac turpis blandit blan.

\paragraph[?]{Ipsum}
Nunc placerat libero vel mauris dignissim quis porttitor felis accumsan. Sed condimentum iaculis ultricies. Vestibulum accumsan volutpat mi ac ultricies. Mauris luctus luctus facilisis.


\end{document}