serializing variables

[Anon]

I'm just beginning to work with cookies.
I understand that there is a limit of 20 cookies that can be set on a browser by one server.Is there any way around this limitation?
In order to speed up access to the information that I'm delivering I want to maximize the data that I put in a cookie. I was thinking of using explode() and implode() to compress data into the cookie.
I working on this I found that there is a function called serialize(). What does it meat to serialize a variable. I understand that it:

returns a string containing a byte-stream representation of value that can be stored anywhere.
and
This is useful for storing or passing PHP values around without losing their type and structure.

However, this does not make sense to me. I though data type and structure were irrelevent with PHP. I attempted to look it up via google. I only found references to Java, Icould not understand what serializing variables is.
A url or explanation would be greatly appreciated.

Bryan

[cordex]

I use serialize() (and, of course, stripslashes() and unserialize()) for passing complex variables (such as arrays) which wouldn't otherwise be able to be transferred over a URL.

-Ben