Twitter announced last month that it was going to offer its ad platform — which consists of promoted tweets, accounts, and trends — to 100,000 accounts from small businesses, and now the company has started selling the ads to its new customers. Of course, this means that you should be expecting more ads in your timeline on mobile and on the web. The new service is in partnership with American Express, and for now only a small group of cardmembers will be sent an invitation to use the ad platform. Businesses that sign up will get $100 in ad credits from American Express, which will go towards bills that are based on how many followers a business' account receives and how much engagement promoted tweets got. Twitter says that it'll automatically promote the "best" tweets from a company, and it'll recommend promoted accounts in the "who to follow" list.

The move is another in a long line of attempts by Twitter to monetize the free-to-use service. The danger, of course, is that users will be pushed away by an influx of commercials cluttering their timelines, but for now Twitter seems to be straddling that line well. While Twitter is starting off small with a select number of American Express' customers, the company says it'll eventually open up the ad platform to other merchants around the world.