How to choose a good web page title

Creating the best page title will increase your audience by improving the position of your pages in search engine results. But what is an optimal title?

A good title should have the following qualities:

Experience from webmaster shows that a title may be changed further after the publication of the page, it is not a problem. If the new title is better than the former that can only improve the hearing.
However, changing the title frequently depending on the news would be a bad idea, it would be a signal of spam and the page would be penalized by search engines.

The <title> tag, length and content

The title should ideally be contained in the <title> of the head section in the HTML code, bound for the search engines, and be included in a <h1> tag for visitors.
The engines can supply the absense of <title> from the page content, however this tag is preferable, it is especially used by the diagnostic tool of Google Webmaster Tools.

If you use a CMS, all will be generated automatically. With static pages, you should create a template. The PHP code is as follows:

<?php
$title="your optimal title";
?>
<head>
<title><?php echo $title; ?></title>
</head>
<body>
<h1><?php echo $title; ?></h1>

etc...

So you'll need to write the title only once, in the source code.

Ideal length in the <title> tag

This length is especially important if the same title is used in the <title> and the <h1> tags. The first is shown by default by search engines, the second is used in SERPs only if the <title> tag is missing.
This length is around of 60-70 characters. We must avoid a title of one or two words, because the search is too general and the title will not participate in the ranking of the page.
Conversely a title too long will be truncated in search results pages. It may exceed the length shown as its content is taken into account independently of what is displayed, but beyond 120 characters it could be considered as a spam attempt.

What keywords?

The title in the <h1> tag is one of the the most important criteria for indexing and positioning. It should contain the essential keywords for the page, keywords that the user types into the search bar to reach your article.
The text in the <title> tag only serves to link your page, it does not participate in its ranking but should incite users to click on the link in the engine results. It must both accurately describe the content and incitate to view it.

The title is primarily intended for the user, it must be an intelligible sentence and not a series of keywords. A page will be penalized if the title seems clearly designed to manipulate the search engine.
The less keywords the title contains and the more they will get importance. This is the current competition on the keywords that will determine the length of the title. So we must add as many words as necessary to suppress any ambiguity between groups of keywords that could correspond to different contexts.

Domain name in the title

Is it useful to put the domain name in the <title> tag? It's a way to promote the site's name where it appears as a reference, which is contradictory.
This can affect negatively its ranking as it refocuses queries on the domain name. To place it at the end of the title is a lesser bad solution if it is thought necessary.

A title should it be a question or the answer?

If your page responds to a question, the title should it correspond to the question or rather sum up the answer?
For example, for the question "What is a good web page title", the answer can be summed up in "An optimal title is attractive and describes accurately the contents".
Which of these two sentences, the page title should it take?

Based on my experience of search engines now, I would say that title in the form of question would be the best option in general.
The engines do not seem smart enough to find an answer in the index corresponding to a question from a net surfer.
Furthermore, the user does not necessarily ask a question but could search for a word or a phrase like "Naomi Watts and Peter" when the question is "Who is Naomi Watts' father?". The ranking will likely be more competitive on the first query than on the second, and since the response is included in the content, its presence in the title is less important.

If the content answers many questions, it is better to place a summary in the title.