Twitter now makes its suite of advertising solutions available to businesses of all sizes via their self-services interface. Advertisers are offered 2 solutions:
More suited to direct response advertising, promoted tweets enable advertising to have one of their tweets show in the newsfeed of users within their targeted demographic as shown below in blue. A web user's Twitter news-feed is one the most high profile pieces of advertising inventory on the Internet and so this provides advestisers with a fantastic opportunity to reach their target market to drive leads and sales.
This solution promotes your Twitter account to users in your target demographic in the "who to follow" section on the right hand side of the screen as shown below in red. This is suited to companies looking to build their followers base on Twitter. This is not likely to be a driver of immediate sales but will build the number of the followers that a company has; these followers can be promoted to over time via regular tweets.