Star Rating issue..???

Hey i am working as a SEO exexcutive…
I have one question or doubt ..I want to know related star rating(which depends on public reviews)..As i told you i am working as executive ..So my question is?
Why rating shows on other website,but star rating is not shown on itself website…Why this is so..
If i want to show rating on my website also ..Then how's it possible…