FileField provides an "File" field type to CCK. It provides many advantages over
the Drupal core "Upload" module including:

 * Per-field upload control (file extensions, file size).
 * Per-node upload size limits.
 * Multiple fields per content type.
 * Customizable paths for saving uploads (plus token support for dynamic paths).
 * Icons for uploaded file types.

Most importanttly, it's a prerequesite for imagefield.