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.
Sending data to PHP from an HTML form is easy.
Comparison Operators allow you to compare variable values against values to determine whether an event should trigger. You use Comparison Operators in Loops and If Statements.