What does `strlen()` function return in PHP?

The strlen() function in PHP is used to determine the length of a string. It returns an integer value that represents the number of characters present in that string. This includes all characters such as letters, digits, punctuation, spaces, and any special characters.

For example, if you call strlen("Hello World"), it would return 11 since there are 11 characters in that string, including the space between "Hello" and "World".

While the option that mentions the total number of characters including spaces might seem closely related, the primary emphasis here is on accurately defining what strlen() specifically returns: the length of a string as a total count of all character elements, which is summarized well in the selected answer. The other options miss the mark in defining the specific functionality of strlen(), such as mixing it up with word count or size in bytes, which are handled differently in PHP through other functions.