What are the best practices for defining and assigning values to variables in PHP scripts?

When defining and assigning values to variables in PHP scripts, it is important to follow best practices to ensure readability and maintainability of the code. One common practice is to use meaningful variable names that describe the data they hold. Additionally, it is recommended to initialize variables before using them to avoid potential errors. Lastly, consider using constants for values that will not change throughout the script.

// Example of defining and assigning values to variables in PHP
$firstName = "John";
$lastName = "Doe";
$age = 30;

define("PI", 3.14);