Meaning of “according to” - Learner’s Dictionary

according to

preposition us uk /əˈkɔːdɪŋtuː/
Extra Examples
The whole evening was a disaster, according to Sally.Holidays in the UK are becoming more popular, according to a recent survey.There'll be severe water shortages this summer, according to an article in today's paper.The books are categorized according to subject.The children are grouped according to their ability.

B1 as said by someone or shown by something:

According to Susie, he didn't even have a girlfriend.
According to our records, she was absent last Friday.

B2 based on a particular system or plan:

Children are allocated to schools according to the area in which they live.

(Definition of “according to” from the Cambridge Learner’s Dictionary © Cambridge University Press)