Functions in PHP are blocks of code that can be reused throughout a program. They help in organizing code, improving readability, and reducing redundancy. PHP provides many built-in functions (like strlen()), and also allows users to define their own functions.
Functions help organize code, make it more reusable, and can take inputs (parameters) to produce different outputs based on those inputs. Like how when we call the function greet, it print out the name Tim.