Question: I am looking to include rich snippets into a site I'm building for a customer. The customer requested this because he wants his organic search results to show his review stars.

I have read some blog posts about Rich Snippets but none of them show or tell me what to actually change in the source code for those review stars to show up in Google.

I've got the following data at my disposal:

* Company name
* Site name
* Review Average
* Total Reviews

To add upon my story (in hopes of making it more clear):

I'm working on a webshop. Let's call it example.com. After customers made a purchase in the webshop they receive an email asking them if they want to rate the webshop. My client wants those ratings (stars) visible in the organic search results. I've learned that rich snippets are required to do this. What I do not understand however is how these rich snippets should look, where I need to place them, and especially. What type of rich snippet I need to do this.

Answer: 
Google documents their [Rich Snippets](https://developers.google.com/structured-data/rich-snippets/). For your case:

* ~~[Reviews](https://support.google.com/webmasters/answer/146645?hl=en)~~
* ~~[Review ratings](https://support.google.com/webmasters/answer/172705?hl=en)~~
* [Enabling Rich Snippets for Reviews and Ratings](https://developers.google.com/structured-data/rich-snippets/reviews)

~~The examples still use the inactive vocabulary Data-Vocabulary.org, but as explained in the header, you probably want to use the vocabulary Schema.org now.~~

The relevant Schema.org types would be:

* [`Review`](http://schema.org/Review)
* [`Rating`](http://schema.org/Rating) / [`AggregateRating`](http://schema.org/AggregateRating)

You can use the vocabulary Schema.org with different syntaxes. For marking up visible content on webpages, you’ll probably want to use Microdata or RDFa (see [my answer about their differences](https://stackoverflow.com/a/25888436/1591669)).

For checking your structured data, you can use Google’s [Testing Tool](https://developers.google.com/structured-data/testing-tool/).
You have to manipulate your code for do that.  

The full reference can be founded here <http://schema.org>  

and the section for Aggregate Rating is here <http://schema.org/AggregateRating>

When you're done, you can test your work with the google tool here <https://www.google.com/webmasters/tools/richsnippets>

Hope it helps