What is PHP?
PHP – a script language that was created for web development as a widely use Hypertext Preprocessor. For creating dynamic web pages, PHP code is embedded into the HTML source document and interpreted by a web server with PHP processor module. On most operating systems and computing platforms PHP is available as a processor for most modern web servers and as standalone interpreter.
PHP code is processed by an interpreter application in command-line mode performing desired operations and creating program output on its standard output channel, as a general programming language. For developing dynamic web page content any PHP code in a requested file is executed by the PHP runtime. It ca be used with many relational database management systems and can be deployed on most web servers, multiple operating systems and platforms. It is provided as a freeware, also the PHP Group offers the complete source code for users to develop and manage for their own use.
This scripting language has been especially created to serve-side web development where PHP generally runs on a web server and also can be used for command-line scripting and client-side GUI apps.
PHP scripts can also be deployed in executable format using a PHP compiler in order to speed up execution time and not have to compile the PHP source code each time the web page is accessed, as the PHP source code is compiled on-the-fly to an internal format that is easy to be executed by the PHP engine. Code optimizers look to reduce the runtime of compiled code by decreasing its size and making other changes that can reduce the execution time with the scope of increasing performance. There are frequent opportunities for code optimization and that is the nature of the PHP compiler, one example of code optimizer is the eAccelerator PHP extension.
To reduce overhead for high load PHP servers is to use an opcode cache which works by caching the compiled form of a PHP script in shared memory to eliminate the overhead work by caching the compiled code anytime the script runs. Many functions that are available in the standard PHP build are similar for C programmers, also PHP includes free and open source libraries with the core build. PHP is a 100% Internet-aware system containing modules for accessing FTP servers, multiple database servers and embedded SQL libraries such PostgreSQL, MySQL and SQLite, LDAP servers and many others.