Starting Monday, some Twitter users will be able to buy products directly from a tweet, as the social media company takes a bigger step toward an e-commerce strategy that could draw in more dollars and attract a larger audience. The initiative launches with a small group of brands, artists and charities that will start posting products for sale in tweets shown to a small percentage of users. Sellers include Burberry, Rihanna and the nonprofit group (RED). Over the next few months, the company expects to broaden the list of sellers and increase the visibility of its e-commerce tweets as the holiday shopping season approaches. Re/code first reported on the planned commerce initiative back in January and said in July that Twitter would roll out the service in time for the holidays.