I'm creating a web site that translates documents and then sends the translated document as an attachment via email to the customer.

But, I'm wondering if the files are large, it may be better to store the document on the web and send an email link to the customer instead.
Right now the email client pulls the file and attaches it to the email and sends.

How are files stored on web sites and links generated, non-maunually?
What would a script like this be called?
Thanks.

It appears there are many ways to approach this issue, depending on your requirements and the types of documents you are storing.

First, your way:
It seems you are already creating the document, because you are able to send it. I would suggest reading up on file handling with PHP.

http://www.google.com/search?hl=en&q=php+file+handling

Now, a different approach:
If they are plain text documents, and you don't need an actual downloadable document, you could simply store the contents in a database. Once stored you could link to a page that takes variables and translates accordingly.
ex: http://yoursite.com/translate.php?do...ish&to=spanish
Then translate.php could grab the contents of document 15 from the database and translate it from english to spanish.

It would definitely depend on the platform/language that you use for your website. Your probably also need to look at how to secure access to your customer' documents / folders.

Customers, especially business customers, will not be confident if inside the email your provide URL link to the document, which does not ask for customer name and password, or requests some other form of authentication.

Another rewarding addition to your document delivery channel could be so-called WebDAV, where your customer can use FileExplorer instead of Internet Explorer.

If you use modern CMS, such as liferay.com, all these requirements can be addressed with little effort.