Title tag is missing
This means that the URL in question does not have a title tag present in the HTML.
Why is this important?
The title tag is considered important to help both users and search engines to quickly understand what content they can expect to find on the page.
The title tag is considered one of the most important on-page SEO factors, so if it is missing this represents an issue that may affect search engine rankings and click-through-rate from the search results.
What does the Hint check?
This Hint will trigger for any internal URL that has no <title> in the <head>.
How do you resolve this issue?
This Hint is marked 'Critical' as it represents a fundamentally breaking issue, which may have a serious adverse impact upon organic search traffic. It is strongly recommended that Critical issues are dealt with as a matter of high priority.
You will need to look into the page templates/scripts/plugins to understand why the title tag is missing (which is a standard feature on any modern CMS), and ensure that a fix is put in place to set a title tag - which may require developer assistance. It is considered best practice to try and include the main target keywords for the page in the title, whilst also communicating 'what the page is about.'