You can create useful and well formatted web pages with HTML, but with the addition of PHP and MySQL you can collect data from your users, create specific content on the fly, and do many other things that simple HTML alone cannot do. You can use PHP right inside your already existing HTML content, or put HTML tags right inside your PHP coding.
PHP and MySQL complement each other to do what neither can do alone. PHP can collect data, and MySQL can in turn store the information. PHP can create dynamic calculations, and MySQL can provide it with the variables it uses. PHP can create a shopping cart for your web store, but MySQL can keep the data in a format PHP can use to create receipts on demand, show current order status, or even suggest other related products.
Although PHP and MySQL can each be used independently, when you put them together it opens up countless possibilities for your site. It is becoming more and more necessary to deliver dynamic content to keep up with the demands of web surfers and their desire to have information instantly delivered to them online.
WordPress is one of the most popular PHP scripts available today, and it allows people with little to no coding knowledge to put up a professional website in minutes. However, if you took the time to identify exactly what you wanted from your blog website, and put in the effort to learn the PHP code necessary to accomplish those results, you could create your own script without all of the extra, unnecessary features included in the WordPress package.
Many open source scripts are filled with endless possibilities for your website. But what happens if you never use 90% of those features? The space those features occupy on the server is wasted, and your website has to comb through it all to determine which features to load and which to ignore when someone visits your website.
By taking the initiative to learn the PHP code required to design a website with only the features you require, and then designing efficient MySQL queries that will populate your website quickly with only the information necessary, you could have a screaming fast website with excellent dynamic content.