How does google collect tweets?

Google displays tweets in their 开发者_如何学JAVAreal time service. I'm just wondering how they collect these?

Google has access to Twitter's firehose of tweets. It is a realtime stream of all public tweets published through Twitter.

My guess would be using the Twitter API.

I am sure google has access to the twitter API.

The Google search also includes the "Search in Twitter". Keywords are also searched under twitter, and the results are posted. I guess..