Ytdyklly

This is not a question but a statement.

Many MWEs include code like:

usepackage{float}

% etc

begin{figure}[H]% or begin{table}[H]

% figure/table code (e.g. begin{tabular}...)

% etc

which has the effect of placing the float (figure or table or ...) at that exact position in the document no matter how bad it will look with respect to spurious white space. The effect is to turn the float into a non-float but with the option of adding a caption. Often the question is about an undesired position of the float which is what the [H] option often leads to.

If you really want a float to be a non-float then don't call it as a float e.g.,

begin{tabular}

% tabular code

and if you need a caption use the caption package. For example

usepackage{caption}

% etc

begin{center}

begin{tabular}

% etc

captionof{table}[Lot entry]{Nonfloating table}

label{tab:X}

end{tabular}

end{center}

% etc

LaTeX tries very hard to position floats in a pleasing way in a document via the optional float parameters [htbp]. If you think you know better then good luck to you.

A comprehensive discussion about floats and what you can do with them is in the 43 page chapter 6 of Frank Mittelbach & Michael Goossens The LaTeX Companion, Second Edition Addison Wesley, 2004. (I understand that there might be a Third edition sometime in the future). The chapter includes details of how you can adjust the allowable spaces for top (t), bottom (b), and here (h) floats.

[H] is often (perhaps usually) misused but it isn't heinous, and the person who originally came up with the syntax is of course extremely honourable.

As egreg commented below the (non)-question, if an image or table is a non-float it shouldn't need a caption so the markup can be simply tabular or includegraphics with no surrounding float container so no need for [H]

However there is a use case where H can be useful. It is not really [H] for Here it is [H] for Humans are better at choosing float positions. If you are prepared to take full control, use [H] on all your floats and float them by hand by moving the environment in the source, and if necessary re-writing other parts of the page to help make things fit, then for some documents you can surely get better results. Of course there is a very high maintenance cost to this as any edit invalidates all the positioning and you have to check all the page breaks again, but if you have just spent ten years writing a book, spending a week at the end hand tuning float positions isn't necessarily the wrong thing to do.