Understanding find with atime, ctime, and mtime

1. atime — access time = last time file opened
2. mtime — modified time = last time file contents was modified
3. ctime — changed time = last time file inode was modified

Numeric arguments can be specified as:

+n for greater than n,
-n for less than n,
n for exactly n.

Note that «less than» means «strictly less than», so -mtime -14 means «last modified at the current time of day, 13 days ago or less» and -mtime +14 means «last modified at the current time of day, 15 days ago or more».