SAN FRANCISCO — Apple is not known for being social — rather, it is known for being buttoned up about everything it does. But on Monday, the company confirmed that it had bought Topsy Labs, a research company that could help Apple better understand what people are talking about on social media networks like Twitter.

Topsy focuses on analyzing the half a billion messages sent over Twitter every day. The company has indexed every tweet ever sent and has made them searchable, much like Google does for the web. The company also helps clients analyze tweets for various business trends.

While Apple has built some of its software to work with Twitter’s service, it remained unclear why a hardware maker like Apple would be interested in Topsy. Apple was not giving any clues.