This has me stumped !

Craig,

I see; no worries! This should be simple enough :)

Concatenation is simply the act of appending one thing to another (see Merriam-Webster for more).

In PHP, the character used isn't as intuitive as in other languages (frequently, the plus sign [ + ] is used to represent this), but the usage is the same. To help understand it, try to think of it simply as the addition operator in basic mathematics:

x + y = result

In PHP, you would write that same statement as:

x . y = result

The ' . ' simply replaces the ' + ' in PHP.

So, if my full name is Erik McClintock, and I had my first and last names stored in their own variables, I could echo my full name by appending the lastName variable to the firstName variable (with a space added in the middle for readability), as follows:

$firstName = "Erik";
$lastName = "McClintock";

$fullName = $firstName . " " . $lastName;

echo $fullName;

So, here, we declare both the firstName and lastName variables, then declare a new variable $fullName to hold my full name, and assign it to be the result of linking (or "concatenating") my firstName, a space in between, and then my lastName. Thus, when we echo $fullName, the value we'll get will be "Erik McClintock".

You could add my fullName into a sentence with some simple concatenation, as well:

echo "Hello, my name is " . $fullName . ".";

This would echo "Hello, my name is Erik McClintock."

The . "."; at the end of the statement is not adding another concatenation, it is adding a period at the end of the sentence. This is really where the PHP character of the dot can be off-putting.

That same thing written without the space (which can make it look a little confusing when you're first learning it) would look like this:

$firstName = "Erik";
$lastName = "McClintock";

$fullName = $firstName . $lastName;

echo $fullName;

And that would produce "ErikMcClintock". There is only one ' . ' used to concatenate one thing to the next in your statement. If you had a word broken up by syllables and you wanted to echo it out put back together, you would do the following:

$firstSyllable = 'con';
$secondSyllable = 'cat';
$thirdSyllable = 'en';
$fourthSyllable = 'ate';

$wholeWord = $firstSyllable . $secondSyllable . $thirdSyllable . $fourthSyllable;

echo $wholeWord;

$wholeWord then would echo 'concatenate'. Notice there is only one dot between each variable to append the previous to the next.

In the code you posted, you're adding too many ' . ' to concatenate. If you think of the situation as needing plus signs ' + ' to work, it may be easier to visualize, and you can then simply replace the plus signs with the PHP dot character.

Does this make any more sense?

Erik