In PPC, audiences

Policies that govern the content and forms of advertising accepted by the search engines. Every time you create a new ad/keyword/etc., it will be submitted for editorial review to ensure guidelines ar [..]

 

The @ sign is used to call out usernames in tweets, like this: Hello @Twitter! When a username is preceded by the @ sign, it becomes a link to a Twitter profile. 

Depending on your Page’s category

A Facebook feature that shows you all of your scheduled content, as well as past content posted to your page.

A setting

Additional incentives

A set of keywords, ads and bids that is a key part of how your account is organized. Each campaign is made up of one or more ad groups

The order in which your ad appears on a page in relation to other paid ads. An ad position