Cron is basically a task scheduler, which runs your selected job at a particular time of day. They are great tools to do repetitive tasks which you might not remember or simply don’t want to do manually. The actual cron jobs are stored in file called crontab. You can directly edit this file from shell or use your control panel’s cron tool to set your crons.
This is what a typical crontab file looks like:
0 * * * * /bin/php –q /home/user1/public_html/sendstudio/users/send_emails.php
0 * * * * /bin/php –q /home/user1/public_html/sendstudio/users/send_autos.php
You can almost do any kind of job with crons. Some of which are :
Backing you database
Sending mails to your members
Cleaning temporary files
Updating softwares
Running applications.
As a small example, suppose you have a website of your own, with many clients. You need to periodically mail them about new rules, etc. You can run the cron services for this depending upon the needs, you can have it send mails, either hourly, daily or weekly. If you have a website for enthusiasts, cron helps the clients by providing info for any upcoming events and sends notices to them about the events taking place.