# Large projects would be unmanageable without functions because the problem of repetitive code would bog down the development process
# A function accepts values, processes them, and then performs an action (printing to the browser, for example), returns a new value, or both.
PHP has 2 types of functions
1. Language defined functions2. User defined functions
Language defined functions
PHP has hundreds of built-in functions . For example strlen() returns the length of a string, in characters .
User defined functions
You can define your own functions in PHP using the function statement. A function name can start with a letter or underscore but not a number. Variables names are case sensitive in PHP, function names are not.
