Of course, read the docs. However, here's a very short answer.
1. To model muldimensional arrays, (hashes, etc.) An element of an array must be a scalar, so it can't be another array - but it can be a reference to an array.
2. It is usual more economical to pass an array (or hash) reference to a sub (and dereference as needed inside the sub) rather than passing the whole array (or hash.) And when passing several arrays (or hashes) to a sub, they get flattened into a single list and lose their integrity; but you can pass several array or hash references to a sub and then dereference inside the sub.
Of course, the language could have been designed so that references only appear behind the scenes and aren't handled by the user, but then likely a lot of flexibility would have been lost.

In reply to Re: Why use references? by chas
in thread Why use references? by w3b

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.