PHP is a server-side scripting language commonly used for web development. It allows embedding scripts into HTML files which are then executed on the server to produce dynamic web page content. PHP scripts can connect to and manipulate databases like MySQL. PHP files have a .php extension and contain text, HTML tags, and PHP scripts. Basic PHP syntax includes using <?php ?> tags to embed PHP code and declare variables starting with $ to store values. Common string functions include concatenation, strlen() to get string length, and strpos() to find a substring position.

2. PHP is a server-side scripting language, like ASP

3. PHP scripts are executed on the server

4. PHP supports many databases (MySQL, Informix, Oracle, Sybase, Solid, PostgreSQL, Generic ODBC, etc.)

5. PHP is an open source software

7. PHP files are returned to the browser as plain HTML

9. MySQL is ideal for both small and large applications

10. MySQL supports standard SQL

11. MySQL compiles on a number of platforms

13. PHP is compatible with almost all servers used today (Apache, IIS, etc.)

14. PHP is FREEWARE.

18. A variable name can only contain alpha-numeric characters and underscores (a-z, A-Z, 0-9, and _ )