What is the difference between client side and server side scripts?
There are several different scripting languages in use on the web, html, javascript, php and asp to name just a few - now some of these are client side scripts and some are server side, so what's the difference? Right first of all I'll explain what it is they mean by client side - this means that the scripts are processed on your machine, in other words these scripts e.g. HTML and javascript will work irrespective of whether you have an internet connection. The client is another word for your browser e.g. Internet Explorer. Conversely server side scripts must be performed on the server - if you think of a server as simply a large external disk drive that lives on somebody elses machine you won't go far wrong. PHP is a server side language and is used in conjunction with html in for example forms. The HTML bit is the form that you fill in online and when you press submit button the contents are sent to a php script on the server for processing - like in a post office i.e. you write the letter (the html) then take it to the post office (PHP) and the PHP makes sure it is put on the van to the correct destination.
What is mySQL?
Aha! mySQL is the part where all of your information is stored and sorted - like in a post office! It is your database (a table based structure). OK back to the post office - you go into the post office and fill in a form to tax your car (html) the man (or woman) behind the counter (PHP) takes your completed form and your money and puts your money in the till (a table in mySQL) and you wait (like you do) until the man (or woman) comes back with your new tax disk (he(or she) has retrieved it from another table in the mySQL database) the post person returns it to you and you go away happy.
PHP is the man in the middle - let's try a new scenario - this time you go into a restaurant. You have a look at the menu (HTML) and choose whatever you like (money no object here) The waiter (PHP)
then takes your order and nips off into the kitchen to process your order. The Chef (mySQL) then gives the waiter your meals and the waiter (PHP) delivers them to your table. So the HTML is the front end - the PHP is the middleware and the mySQL is the back end in the chain.
