Indicates a source of information, meaning 'according to (someone/something)'. Used to attribute statements to reports, people, or data.
気象庁によれば、明日は台風が接近する見込みだ。
According to the Meteorological Agency, a typhoon is expected to approach tomorrow.
友人の話によれば、彼は来月転職するらしい。
According to my friend's story, he seems to be changing jobs next month.
調査によれば、その地域の高齢化率は年々上がっている。
According to the survey, the aging rate in that area is increasing year by year.