Why does the document class book add so much spacing?

Question

I have a LaTeX document with:

\documentclass[12pt]{report}

And most of the spacing between paragraphs and images look like this:

When I just change the document class to:

\documentclass[12pt]{book}

Some pages contain way too much space either between paragraphs or between paragraphs and chapter titles or between paragraphs and images.

The same piece becomes:

How can I remove this spacing and what causes it?

The piece of code of that part is:

% ...

\vspace{20pt}
\begin{figure}[H]
    \centering
    \includegraphics[width=350pt]{img/javascript.jpeg}
    \caption{Esempio di mancanza di scoping in Javascript. \\Fonte: https://dev.to/murithi/scope-in-javascript-e5e}
\end{figure}
\vspace{20pt}

\par Questo è solo un esempio di come in alcune situazioni si rischia di perdere molto tempo nel cercare di 
sistemare problemi derivanti per lo più da funzionalità poco intuitive del linguaggio.

\par L'unica eccezione all'utilizzo di tale linguaggio sarebbe lo sviluppo di prototipi veloci che poi non saranno 
più mantenuti o utilizzati in futuro.

\subsection{Interesse nei linguaggi tipizzati}

\par Ho avuto il piacere di studiare e scoprire Haskell qualche anno fa per conto mio.

% ...

This is very probably due to the default \flushbottom directive and the [H] option for figures. Try with \raggedbottom in the preamble. — Bernard, Dec 04 '17 at 20:40
@Bernard That was it. If you can put it as an answer I'll accept it. — Shoe, Dec 04 '17 at 20:50
@Shoe - Because, in many documents, deploying the [H] sledge hammer tends to create more problems than it solves. If you believe strongly that you have no choice but to override LaTeX's algorithm for placing floats, at least replace [H] with [ht!]. — Mico, Dec 04 '17 at 20:53
Because forcing the placement of a float at a fixed place very often results in extra-long so-called ‘rubber lengths’. — Bernard, Dec 04 '17 at 20:54
@Shoe latex floats figures to avoid getting bad white space, so by using [H] (so disabling floats) you are by design opting to get bad white space as a price to pay to never allow figures to move. — David Carlisle, Dec 04 '17 at 20:59
@Shoe - [H] will occasionally cause real trouble (specifically: big gaping holes on a page), whereas [ht!] won't. For more information on this topic, see the posting How to influence the position of float environments like figure and table in LaTeX -- and esp. Frank Mittelbach's answer. — Mico, Dec 04 '17 at 21:28

Why does the document class book add so much spacing?

0 Answers0