Search Engine Forums, SEO Forum

There are many type of ad extension such as

Location
You can Extend your ads with location information

Product listing ads
Use product information from Google Merchant Center to create and target ads

Sitelinks
Extend your ads with links to sections on my site

Call
Extend your ads with a phone number

Social
Increase the social relevance of your ads by associating them with my Google+ Page

Dynamic search ads
Use your website content to target your ads

Offers
Extend your ads with promotions

App
Extend my ads with a link to a mobile/tablet app.

Ad extensions are additional pieces of information about your business, like a phone number or a link to a specific page on your website, you can add to your ads. ... Including ad extensions can improve the visibility of your ads, which can lead to more clicks and improve your ROI.

Thankyou for sharing this useful information!