used to indicate a source of information (as in 'according to ...'); shows that what follows is based on a report or source.
新聞によれば、今朝大きな地震があったそうだ。
According to the newspaper, there was a major earthquake this morning.
報告によれば、売上は去年より10%増えた。
According to the report, sales increased by 10% compared to last year.
友人の話によれば、彼は今海外にいるらしい。
According to a friend's story, he seems to be abroad now.