Cron Jobs are kind of scheduled transactions. To be able to use at first you need to create PHP file. This PHP file will do whatever you want to do. For example you can update database table or email customers newsletter. It is just simple PHP file as you know.

Then you need to define cron job to run this PHP file. To be able to define cron job, you need to go to your control panel of you WEBsite. You will see cron jobs in your control menu and when you try to create new one it will ask you which PHP file will you run and its location on the server. Then you will determine when you want run it.

That’s all you need to do to run a PHP file automatically.

For example, you want to send yourself daily report about current WEBsite visitors like how many users visited your WEBsite, which pages viewed most etc. You write a PHP page that queries related fields from your database and then send them  to your email address. Then, you define a cron job from your WEBsite control panel and define this PHP file and to send report to you at 7 AM in the morning.

So every 7 AM in the morning, cron job will run this PHP file automatically and send you daily report you want.