Coding languages like all software has versions. These versions offer improvements, and changes over time. This means that functions that work in some versions do not work in others. So you need to verify which version of PHP code has been written for, and also think about using common functions in your code to prevent issues with running it on new versions of PHP.
Using includes you can reuse the same code in multiple scripts.
Since Variables in PHP do not need to be declared you can run into issues such as trying to add a String to an Int. You also may have issues if you misspell a variable. […]