Question: I know it's possible to have an array within an array like this.

```
Array01 (

[0] => Array
    (
        [0] => 40292633
        [1] => 412
    )

[1] => Array
    (
        [0] => 41785603
        [1] => 382
    )

[2] => Array
    (
        [0] => 48792980
        [1] => 373
    )

[3] => Array
    (
        [0] => 44741143
        [1] => 329
    )
)

```

Can you have an array in an array in an array like this?

```
Array01 (

[0] => Array
    (
       [0] => Array
       (
           [0] => 40292633
           [1] => 412
       )

        [1] => Array
       (
           [0] => 41785603
           [1] => 382
       )
    )

[1] => Array
    (
        [0] => 41785603
        [1] => 382
    )

[2] => Array
    (
        [0] => 48792980
        [1] => 373
    )

[3] => Array
    (
        [0] => 44741143
        [1] => 329
    )
)

```

What I'm curious about is how far can this go, how many arrays can you have in an array?

Answer: 
What you have described in your first example is a "simple" bi-dimensional array - an "array of arrays" - in which you must use two indexes to access the required data.

In the second example you have described a mixed dimensional array - for some elements to be accessed you need to provide three indexes, for others, only two.

AFAIK, an array' size (and any other variable for that matter) is limited only by the memory available to the PHP interpreter (and by the other variables that are already present in the memory).

**Update: Clarification**

There is no hard limit imposed on the array depth/dimensions by design in PHP. You can have as many dimensions as you want, provided that:

1. You don't hit the memory limit
2. You don't go over the PHP's elements limit for one of your arrays^

^*There is a limit on how many elements an array can have - [RiggsFolly](https://stackoverflow.com/users/2310830/riggsfolly) has provided a link to [this answer](https://stackoverflow.com/questions/3036957/php-do-arrays-have-a-maximum-size) on that particular topic, if you're interested.*
You could test it by yourself

```
<?php
$i =0;
$array = [];
$a = &$array;
while(true) {
$a = &$a[];
$i++;
if ($i % 1000000==0){ echo $i,' ';};
}

```