An e-mail message attachment is a file sent with an outgoing e-mail message. Standard activities and functions allow outgoing e-mail messages to include attachments. See How to send e-mail with attachments.
A work object attachment identifies a named small file, screen shot image, correspondence, URL or text note that a user or an activity has associated with a work object.
On the standard harness Perform and Review forms, a paper
clip button provides access to add, edit, delete, or review
work object attachments. Correspondence attachments are
permanent parts of the history of the work object and cannot be
deleted or updated.
One work object may have an unlimited number of attachments.
A rule attachment is a file associated with a rule, saved as a separate (binary file rule).