Understanding Functions in PHP

In PHP, a function is a block of code that can be reused multiple times within a program. Functions are used to perform specific tasks and can be invoked, or called, anywhere in a program once they have been declared.

The correct syntax for creating a function in PHP is as follows:

function functionName() {

 // code to be executed

}

The function keyword is used to define a new function, followed by the name of the function. It's worth noting that the function name is case-insensitive in PHP. The code within the curly braces {} represents the body of the function where actual logic resides that needs to be executed whenever the function is called.

For example, let's say we want to create a function named greet that prints a greeting message:

function greet() {
    
    echo "Hello, welcome to PHP functions!";
    
}

To execute a function, we simply need to call it based on its name:

greet();  // Outputs: Hello, welcome to PHP functions!

The other answer options provided in the quiz question such as create NewFunction() {}, new Function() {}, and function: NewFunction() {} are incorrect as they're not valid ways to define a function in PHP.

While writing functions in PHP, it's essential to follow the best practices such as:

1. Function name should be descriptive and indicate to its functionality - makes the code easier to read and maintain.
2. Avoid creating functions that are too large - functions should be kept small and only perform one task.
3. Avoid global variables in functions - as it can introduce bugs because of unexpected side effects.

By practicing these best practices, you can write robust and maintainable PHP code.