Metadata is all the information about a page that you send to a search engine that isn’t visible to your visitors.
There seems to be some misunderstanding about this, as most of the articles I read about SEO metadata seem to imply that it’s just the title, description, keywords and robots declaration in theof your website. Others feel social media declarations like Open Graph tags should be considered metadata as well. W3C states that “The element represents various kinds of metadata that cannot be expressed using the title, base, link, style, and script elements.” That means all these elements from meta to link and script are in fact metadata.
The obvious metadata elements
There are a couple of elements that obviously are metadata elements. You may have already heard of these.
The title element is the main title of a page, represented by the 'title' element.
This is probably the most important element for SEO. Adding the right title to your pages can still have a direct influence on your ranking. Make sure to include the main keyword (or: focus keyword) at the beginning, and end your 'title' with your company or website name for branding.
The preferred length of your 'title' might vary based on the most-used device people use to view your website, but a rule of thumb is that we have to keep a viewable limit in mind these days. An example: if you have lots of mobile visitors, go for a shorter title. It’s as simple as that.
The meta description used to be the short description or summary of the page at hand.
In the old days, it helped Google to tell what the page was about. These days, Google simply reads the entire page and the meta description has become a suggestion for the text displayed in Google’s search result pages. Therefore the content on your page is REALLY important.
Forget about meta keywords now. They’re just used for tags on some social sites. If you’ve heavily optimized your meta keywords, for instance by stuffing it with your focus keyword Bing will consider this spammy. I can relate to that. The influence of meta keywords has become close to zero (and zero for Google).
This is not all when it comes to metadata, but it might help you understand a little bit about the content that you need to be thinking about when writing the copy for your website.