Keychain is a container which saves and retrieves password as and when necessary, at system level.
The passwords (can be password of multiple things which are used to access websites, FTP servers, SSH accounts, network shares, wireless networks, groupware applications, encrypted disk images), private keys, certificates, and secure notes are stored in an application in MAC OS is called Keychain. One can open Keychain by opening Finder from the Dock, click open Applications, then Utilities, there double click on Keychain. In macOS, keychain files are stored in ~/Library/Keychains/ (and subdirectories), /Library/Keychains/, and /Network/Library/Keychains/. The file extension for a Keychain file is .keychian.
The password can be shared with other Apple devices and synced so that passwords can be used uniformly on all apps across Apple devices. This is possible via iCloud Keychain. Keychain Access works in collaboration with iCloud Keychain, to create and manage the iCloud Keychain, one must sign into iCloud with the Apple ID. Please refer the Apple Support link for setting up iCloud Keychain.
Repair Keychain: This is done when Due to any reasons the stored password got corrupted. If the applications refuse to accept the “correct” password and you are being prompted to enter the password multiple times. Then we do Keychain repair. This step is highly recommended in fixing login issues at enterprise level wherein users are supposed to change their log in password every 90 days and the password sync does not happen with, keychain and filevault.
Open the Keychain Access menu > Keychain First Aid. Enter your Username and Password when prompted. Then click on Verify to check for corrupted passwords (red entries). After that select the Repair option.
This article is part of our macOS Basics series. You can check other articles here.