What is shadow file in Linux.

What is shadow file in Unix

/etc/shadow is holding user password related informastion. /etc/shadow file contains one entry per line, each representing a user account.following nine fields separated by colons

What is /etc/shadow file in Linux.
(1) Username
(2) Encrypted password
(3) Last password change
(4) Minimum required days between password changes
(5) Maximum allowed days between password changes
(6) warning
(7) Number of days after password expiration to disable the account
(8) user Account expiration date
(9) Reserve field