There are different standards for microdata. The word microdata just means that data has been embedded in the page. When you start using microdata you must reference which standard you are using with the
itemtype property defines the microdata format for all the children of that
<div>. If you are using the schema.org standard, then data is defined using a heirarchy of types starting with the base type
You can see a list of the different types here: http://schema.org/docs/full.html
I will now explain about custom tag. I don't know about it being custom but I have seen tags like "time" where microdata code looked like this:
The microdata set on the
<time> tag is only valid if there is a parent DOM element that defines the
itemtype. That will tell you what microdata standard is being used. Depending upon that type I can't tell you if it's a valid or invalid microdata format.
Are TIME and TEXT custom made up tags or they are elements that belong somewhere? Can I customize these for my needs?
Custom tags only work in XHTML and HTML5. In HTML5 unknown tags are rendered as
display:block. When you create custom tags and view that HTML in non-HTML5 it will be ignored by the browser as
Microdata has nothing to do with custom tags. You can use microdata attributes and attach data to that tag, but it has no impact on how that tag is handled by the browser. This is true for all microdata attributes.
I would assume that Google indexes microdata on custom tags if the document type is XHTML. I don't see anyone reason for it to ignore the data.
META tags that sit within HEAD of a webpage. What difference it makes when using microdata in them and outside of HEAD of webpage?
Microdata in the
<head> section of a webpage defines data that is for the scope of the entire page. You might want to define that the current page is a
CollectionPage in the header, and then define a bunch of
<div> tags as
According to Google's structured data testing tool if certain microdata is presented for search engines, then it also must be present on webpage's content, otherwise such misleading practice will result in penalty.
This is one of those ambiguous guidelines by Google, and I've read the same thing on their site.
Here's how to clarify what they are talking about:
- You can include microdata in your page header. If that works for you. It is completely valid and correct usage of the microdata standard.
- Google will not display microdata from the header in it's search results. It's not visible to the user.
- Google could penalize you for putting in microdata that does not represent what is on the page (i.e. Google does some magic processing to see if you are trying to trick them).
- Google will index microdata that is defined as attributes on visible DOM elements in the body of a page.
- Google will not tell you when, how or why they will use the microdata. I have microdata on several websites, and Google has never used it. Microdata appears in search results as a sidebar to the right of the results (i.e. search for a popular movie or actor).
There are other search engines out there that support microdata. These crawlers are not as strict as Google.
For example Yandex will index microdata found in embedded JSON-LD objects.
Try validating your microdata using their tool. I find it more accurate than Google's testing tools.