What are Google’s guidelines for structured data to be included in search results?

[makoo]

What are Google’s guidelines for structured data to be included in search results?

[GeethaN]

Quality guidelines
Follow the Google webmasters quality guidelines.
Provide up-to-date information. ...
Provide original content that you or your users have generated.
Don't mark up content that is not visible to readers of the page.

[jayam]

These are the general guidelines that apply to all structured data. These guidelines must be followed to enable structured data to be eligible for inclusion in Google Search results.

[jayammrg]

Add structured data to the steps, tools, duration, and other properties to enable a How-to rich result for your content on the search page. If your page uses images or video for each step, make sure to mark up your visual content to enhance the preview and expose a more visual representation of your content to users.

[chandrao7]

Google will penalize sites which they believe are using structured data markup in scammy ways . There are some other general guidelines from Google, including: Add your markup to the page it describes (so Product markup would be added to the individual product page, not the homepage)