Rich snippets: star ratings, what can be rated?

[deeper]

Hi,
Google supports "ratings", which are widely spread as "5 stars".

They are misused and may be will disappear completely one day, but I will give it a shot.

Google says "specific products and services" can be rated.

So there is no way to let visitors of good informational pages give their vote about the quality of an article and Google will show it in their serps?

[netmeg]

I've seen them for reviews, and I use them myself for events. As far as just plain posts or articles, I dunno.

[deeper]

Reviews, yes, but reading Google help they mean reviews for products and services.

Your ratings for events are shown in the Serps?

[netmeg]

Yep.

[not2easy]

Google has become quite selective about whose snippets are picked up and seen. If you follow the structure and purpose of Rich Snippets (as netmeg obviously does) they are great. There's a right way and wrong way to use them and a fair amount of abuse made it more critical to do it right. Google offers guidelines for that: [support.google.com...]

[deeper]

I don't mind Google being selective, though I can't imagine how to avoid abuse of ratings.

The first step of going the right way is to know what content types may have rich snippets, i.e. are basically supported by Google.

Ratings belong to reviews. O.K. Google help says reviews are possible for "products and services".
They are additionally possible for further content types which Google supports (https://support.google.com/webmasters/topic/4599102?hl=en&ref_topic=4598337), if there is a property called "review". For example recipes. Indeed recipes often show ratings. O.K.

But why do many try to get star ratings for their normal, may be comprehensive informational content, for example blog articles? And sometimes get them? Even "articles" (as schema.org calls this "object" as part of "creative work") is not supported by Google.

Events can have rich snippets, but there is no property "review" for them. I'm not sure, but I think it's the same with videos, some have ratings though their properties at [support.google.com...]

Is this the answer: Try it and may be you have luck? Google is not able to identify the content types reliably or just generous?