Re: Head over heels
A "cron" or "cron job" is a scheduled task. (That's "cron" as in "chronometer" or "chronic", meaning "time".) You have access to a "cron tab", which will allow you to run scripts on schedule to do things like clean up databases, rewrite menus (so they can be served as "static" elements rather than having to be recomputed for every visit), fetch data from outside sources -- that sort of thing. There are restrictions in place to prevent your scheduled tasks (crons) from interfering with other users on the same server, and since there are more users per server on Free Hosting servers, the restrictions are tighter. (If you are running your own server, you can go crazy.)
“Beware of bugs in the above code; I have only proved it correct, not tried it.” --Donald Knuth
"It was as if its architects were given a perfectly good hammer and gleefully replied, 'neat! With this hammer, we can build a tool that can pound in nails.'" -- Alex Papadimoulis (on TheDailyWTF.com)