This update:

• Adds Night Shift for automatically shifting the colors in your display to the warmer end of the spectrum after dark

• Adds Siri support for cricket sports scores and statistics for Indian Premier League and International Cricket Council

• Adds Dictation support for Shanghainese

• Resolves several PDF rendering and annotation issues in Preview

• Improves the visibility of the subject line when using Conversation View in Mail

• Fixes an issue that may prevent content from appearing in Mail messages

For more detailed information about this update, please visit: https://support.apple.com/kb/HT207536 

For detailed information about the security content of this update, please visit: https://support.apple.com/kb/HT201222