Every program that interacts with people responds to a specific set of commands. The set of commands and the syntax for entering them is called the user interface and varies from one program to another. The DOS operating system makes a distinction between internal and external commands.
the reason HTML seems to work even if it has syntax errors is due to browser having built in ways to parse the code meaning it will still show but most likely look way different then you would want.
the code may turn pink due to syntax errors
The answer is : variables
When viewing data entered into a spreadsheet, the columns identify Variable. The variables later can be used on a formula to help you process any sort of data that is implemented within excels' formula system