The Associated Press (AP) was started in 1946 to gather news and record history. The Associated Press has staff in more than 100 countries and is a non-profit cooperative with 1500 newspapers as member/owners. AP develops style guides for all occasions, which are used by journalists and reporters.
Purdue Online Writing Lab has a good overview of the AP style at: https://owl.english.purdue.edu/owl/resource/735/02/ ; however, the AP style has over 5000 entries and continues to grow. If you are a journalist, then it is best to either purchase the AP Stylebook at: http://www.apstylebook.com/ or join the community online at AP Stylebook Online at: https://www.apstylebook.com/online/