HTML5: how to define abbreviation and acronym

In this article you will find out about the distinction between an acronym and an abbreviation.
In order to set a value for an abbreviation (or acronym) do the following: place the acronym or abbreviation in abbr element and set the value using title.
<abbr title="Hypertext Preprocessor">PHP</abbr>
In previous HTML versions to create abbreviations and acronyms elements abbr and acronym were used. But these two elements were in the center of constant disputes.
The first problem was that up till version 7 Internet Explorer simply did not display the value title as a helping tool. To "solve" this problem, people began using the element acronym everywhere, despite the fact that a word might not actually be an acronym.
The second problem was a significant difference between acronym and abbr. Presently, the element acronym was removed from the HTML5, because all the acronyms - are in fact the same old abbreviations, only a bit more trimmed.