Kdtyjb

When I compile my PDF from LaTeX source, do I have to care about all the messages (currently 28) about 'bad boxes'?

The PDF seems fine to me.

It is worth noting that TeX doesn't make the value judgements here.

The user, or more likely, the class file on behalf of the user, has set constraints on the amount by which boxes may overflow, the amount of stretching allowed on short pages etc. TeX only warns if these user-set constraints are exceeded.

So if you are setting difficult material with lots of big unbreakable chunks, that means that the constraints are probably wrong. (They were designed mostly for copy that is mostly text that can be hyphenated and with enough interword stretch to get tight fitting boxes.)

Rather than TeX trying to meet un-achievable constraints and then complaining about failing to meet them, it is better to modify (relax) the constraints. But before doing that you should make sure that they really are un-achievable and it is not just user error preventing tex from finding a good layout.

Some general notes added as requested:

Settings that only affect warning messages.

There are several setting that only affect the messages that TeX sends
out. For example if you know that some boxes will be overfull by 2pt
(and you don't mind this) but you want to be warned for a box that is
1cm too full then set

hfuzz=2pt

this will make no difference to the typesetting, but will suppress
warnings for boxes that are only slightly overfull.

vfuzz

is the same thing for vertical boxes.

Similar are hbadness and vbadness which are a measure of how
bad a box is, typically how much white space has had to be stretched.
the exact number is not usually that relevant but 0 is good and 10000
is infinitely bad (TeX's badness calculation arbitrarily forces any
very bad boxes to this amount).

The parameter tolerance is what tells Tex how much stretching
should be allowed. TeX tries to line-break a paragraph in such a way
as to keep the badness below the specified tolerance.

Good typographic quality would indicate that you shouldn't ignore (or
turn off) these warnings, However sometimes it makes sense. The PDF
version of the MathML recommendation for example is set automatically
by LaTeX from sources primarily designed for the normative HTML
version. Because it has many one or two line paragraphs and many
indented tables and examples, the right hand margin is very uneven
anyway and so allowing the occasional overlarge example to protrude
isn't so bad, it is set with

hfuzz=20pt

vfuzz=20pt

hbadness=2000

vbadness=maxdimen

Settings that don't affect the typesetting of good boxes

TeX3 introduced a parameter emergencystretch which allows extra
stretch to be more uniformly added to a paragraph if the default
stretching does not produce a good break. Setting this to a non zero
value can sometimes help.

Settings that do affect the typesetting.

LaTeX has a command sloppy that sets up looser typesetting

defsloppy{%

  tolerance 9999%

  emergencystretch 3em%

  hfuzz .5p@

  vfuzzhfuzz}

The setting of tolerance makes it rather more sloppy than is perhaps
desirable, and it is probably worth experimenting with just setting
emergencystretch.

The default fussy settings used by LaTeX are

deffussy{%

  emergencystretchz@

  tolerance 200%

  hfuzz .1p@

  vfuzzhfuzz}

For vertical page breaking, if you are getting underful boxes in the
output routine you may prefer raggedbottom rather than
flushbottom as this adds stretchable space at the end of each page
so no page will be underful (but short pages will be silently
accepted). It is possible of course to have something between these
two extremes, that adds glue that only extends a finite amount rather
than fill glue.

The above are the main global settings however every aspect of the
document design affects this. In particular, if the space between
display elements such as lists and displayed maths, and the space
between paragraphs, is stretchy then it it is much easier for TeX fo
find a "good" page break, however this means that there is no vertical
alignment between lines on different pages. especially for book designs
using two page spreads, designers often aim to keep text on a grid
where text always aligns on fixed positions. This usually means that
you have to make all the vertical spaces much more rigid, which
increases the chance of Tex giving warnings about over or under-full
vboxes.

Yes, you should definitely take care of them.

1. Overfull hbox messages tell you that some line sticks out over the right margin;




2. Underfull hbox messages tell you that some line is poorly typeset (or that you've improperly used \ to leave a vertical space (for example, typing two \ in a row);




3. Underfull vbox messages usually tell you that a page is poorly typeset.

How much badness requires action is difficult to say, but I would never accept a final PDF where there's some Overfull hbox.