You may not be able to search for your own Tweets on Twitter after a week, but a marketing research company in the UK can now search all the Tweets Tweeted since January of 2010. This is possible because Twitter just sold Datasift the right to sort through them.

Even though users don’t have access to them, Twitter has an archive of the millions of Tweets that have blasted across its social media network. Now, privacy advocates are condemning Twitter for selling businesses the right to search through all of those Tweets in order to enhance their marketing efforts.

This is a problem for data privacy companies such as Allow. Justin Basini, a representative from Allow said,

This move shows [that] all those throwaway Tweets have suddenly become a rich new revenue stream for Twitter. It has taken a stream of consciousness, analyzed it, bottled it and sold it for profit. And the worst thing is, you never knew it was going to happen."

250 million Tweets are sent through Twitter every day. For an advertiser, this is a treasure trove of market research material. British market research firm Datasift charges clients more than $15,000 a month just to analyze Tweets posted each day to find anything said about their products and services. Imagine what they could do with access to all the Tweets ever Tweeted. Currently, they have a waiting list of 1,000 clients waiting for their chance to sift through your Tweets.

Gus Hosein, of watchdog group Privacy International, said in response to the move, “Twitter has turned a social network that was meant to promote global conversation into a vast market-research enterprise with unwilling, unpaid participants.”

Twitter now joins Facebook and Google in the ranks of social media sites that go to great lengths to discreetly mine the data of users, and then sell it, in order to further market research. And, for now, it seems that Twitter’s sale of access to its archives is fair play. According to the site’s terms of use:

You understand that through your use of the Services you consent to the collection and use (as set forth in the Privacy Policy) of this information, including the transfer of this information to the United States and/or other countries for storage, processing and use by Twitter.

Try saying that in under 140 characters.

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