What is the significance of the error message "parse error, unexpected '='..." in PHP code?

The error message "parse error, unexpected '='..." in PHP code indicates that there is a syntax error where an equal sign '=' is used incorrectly. This error commonly occurs when trying to assign a value within a conditional statement or when defining a constant. To solve this issue, you need to review the line where the error is reported and correct the syntax by using the appropriate assignment operator.

// Incorrect usage of equal sign causing parse error
if ($variable = 10) {
    echo "Value is 10";
}

// Corrected code using comparison operator '=='
if ($variable == 10) {
    echo "Value is 10";
}