A function is a group of statements that can be executed any time you want.

PHP has a number of predefine functions for you to use.

Below given are the different type of funtions available in PHP

• Date functions
• Math functions
• Array functions
• Calendar functions
• Directory functions
• Error functions
• Filesystem functions
• Filter functions
• FTP functions
• HTTP functions
• LibXML functions
• Zip functions
• Mail functions
• Misc functions
• MySQL functions
• SimpleXML functions
• String functions
• XML Parser functions