The company has now said that, although it will be able to archive and reproduce content, users will control the rights to all of their posts.
Twitter also left open the possibility of new advertising campaigns by notifying users that the site will keep the right to serve ads based on web page information and search queries.
Company co-founder Biz Stone said that the new terms are designed to keep pace with growth and change at Twitter, and that clarifying the areas of ownership and advertising are key to the new terms.
"These updates complement the spirit of Twitter," Stone said in an email to users. "As Twitter has evolved, we have gained a better understanding of how folks use the service."
Stone added that the company is open to user comments, and may change the terms based on feedback. User outcry has in the past led to social networks such as Facebook altering their terms and conditions.