What is better, if somebody skip
<title> tag or
<meta name="description" />
or leave empty value:
<title></title> <meta name="description" content="" />
? Or maybe all above has the same meaning for crawlers?
It is better to leave the title tag and description meta tag out than to have them populated with empty strings.
Unique, keyword-rich title tag and relevant description meta tag.
Unique, keyword-rich title tag and no description meta tag.
No title tag and no description meta tag.
Empty title tag and description meta tag.
Same title and description meta-tag on each page
The contents of your
<title> tag is almost certainly the most important on page SEO factor. Leaving it blank is essentially SEO suicide. Not coincidentally, it is also very bad usability as users use it to tell what page they are on and it is also the default title used when a page is bookmarked.
An empty meta description isn't a big deal. It isn't used for ranking purposes and its content may be used as a page's description in the search results. However, if it is blank other content can be used as a page's description so leaving it blank won't actually harm your rankings.