What is causing the "parse error, unexpected T_STRING" in the PHP code?

The "parse error, unexpected T_STRING" in PHP code is typically caused by a syntax error, such as missing quotes or semicolons, or using a reserved keyword as a variable name. To solve this issue, carefully review the code for any syntax errors and ensure that all strings are properly enclosed in quotes.

// Incorrect code causing parse error
$variable = Hello World!;

// Corrected code
$variable = "Hello World!";