There is something called relational databases.

So for example, they might have a table called members, which would have a field (column) tthat has an auto-increasing number, your first, last name, an e-mail and such. From then on, you are referred to as a number. Then they have a table called status updates for example, the fields there are probably another auto-increase number, a field that refers to the number on the member table (so they know who did it), and the text of your status update.

To go further, they probably have a table called status update comments which has another auto-number, a field to reference what auto-number its referring to for the status update, a field that references the member table to know who posted the comment, then the comment text itself.

Also, a database has a 4gb limit, so it may be spread across many databases. A search wields steps to get around the limit, if needed...

Hope this helps.

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