Find is a Linux command use for searching a file or files in a directory hierarchy. It is help full to search for a file or directory based on name, size, type and access/modified time etc and as well as can execute command on results.
Basic Syntax for Find command :
find (name/size/type/access or modified date) ..argument ..argument
Search for file ending .conf
find /etc/ -name *.conf
Search for directories ending with *conf
find /etc/ -type d -name *conf
Search for files ending with .doc and accessed in last 24 hours(or 1 day)
find /home/xyzuser/ -name *.doc -atime -1
Find files modified by minutes
Syntax : find /path/ -mmin
Find files 10 minutes ago
find /etc/ -mmin -10
Find files more then 10 minutes ago
find /etc/ -mmin +10
Find files modified between 10 to 20 minutes ago
find /etc/ -mmin +10 -mmin -20
Find files modified in past 2 days(48 hours)
find /etc/ -mtime -2
Search for files owned by xyz user
find /etc/ -type f -user xyz
Search for directories and change permission to 755
find /home/xyz.com/public_html/ -type d -exec chmod -v 755 {} \;
These are find command example used by every admin most frequently.
For further reading do
man find or man 1 find