What does the '!=' operator signify in PHP?

The '!=' operator in PHP is used to check for inequality between two values without considering their data types. When this operator is employed, it evaluates whether the values on either side are not equal, performing a loose comparison. As a result, it will convert the types of the values being compared if necessary to determine if they are different.

For instance, if you compare a string "0" and an integer 0 using this operator, PHP will treat them as equal since both represent the same value in a loose context. Therefore, if the values are indeed not equal after the necessary type conversions, the expression will evaluate to true. This is a fundamental aspect of type juggling in PHP where types are converted automatically during comparisons.

In contrast, other options reflect different functionalities in PHP. One of them pertains to reference checking, another relates to strict type comparisons, and the last one discusses array manipulation, none of which are applicable to the '!=' operator.