PHP and a normal webpage
HTML describes the page structure. CSS controls presentation. JavaScript can add browser-side interaction. PHP runs on the server and can process requests, validate information, read databases and generate dynamic page content.
PHP and MySQL
PHP is often used alongside MySQL databases. A website can receive a request, use PHP to query the database and then display the relevant information.
Examples of PHP functionality
Contact forms, login systems, member areas, searchable directories, admin dashboards, calculators, content systems and custom workflows can all use PHP.
Why custom PHP can be useful
Off-the-shelf software does not always match the way a business works. Custom PHP can be used when a specific workflow or feature needs to be built around the requirement.
PHP needs good security practices
Input validation, secure authentication, safe database queries, access controls and sensible error handling are important when developing PHP applications.