Loop allows us to execute a statement or a group of statements a number of times until it fulfills a condition.
An array in php is an ordered map that associates values to keys.
In programming languages, a string is a data type that represent a sequence of characters.
If a variable is meant to be contain a value that may change, then, a constant is meant to be contain a value that never change.
In programming, data type is the name of a group of data that has a predefined common set of characteristics.
Variable is a memorable name of computer memory cell(s) that can hold a value during the execution of the program and the value may change.
Get familiar with the PHP basic syntax, the set of basic rules that define the combinations of symbols that are considered to be correctly structured programs.