Apple has acquired social media search and analytics startup Topsy, which specialises in using data from Twitter to track customer sentiment. The Wall Street Journal reported that the deal cost Apple over $200 million.

Topsy competes with firms like DataSift and Gnip to figure out who is influential on Twitter, what terms are trending, and the impact of specific Twitter campaigns.

It is Apple's second acquisition in recent weeks. Last month, it a PrimeSense, which specialises in making 3-D motion detection technology.

The reason behind Apple's latest acquisition is not clear. The company has been making it easier for people to share photos, videos and news through its devices and directly to social networks such as Facebook and Twitter. iTunes Radio could also benefit from Topsy's data on consumer sentiment.

Apple could also use Topsy's technology to its own data, such as information from the App Store.

Getting a better grasp on the hottest topics on Twitter could also help Apple sell more advertising on iPhones and iPads.

Topsy's Twitter tools also could be used to give the iPhone a search feature that isn't available on products running on Google's Android operating system.