What are the main characteristics of PHP as a programming language?

"Using the Hello World! program as a starting point, we will examine the basic elements of the PHP language. PHP has adopted many aspects of the C programming language (the interpreter itself is written in C). However, there are some major aspects in which it differs from C. PHP is an interpreted language: it is not compiled. Instead it is interpreted through an interpreter that parses commands in a script file line-by-line. Any syntax errors, therefore, become runtime errors. PHP is dynamically typed: you do not declare variables or specify a variable’s type. Instead, when you assign a variable a value, the variable’s type dynamically changes to accommodate the assigned value. Variable names always begin with a dollar sign, $."