Generally, you must supply copies representing the entire work being registered.
Unpublished Works: One complete copy. (read details on format).
Published Works: Two complete copies of the best edition (read details).
Works First Published Outside the U.S.: One complete copy of the first foreign edition.
Contribution to a Collective Work: One complete copy of the best edition of the collective work, or a copy of the contribution itself as it was published in the collective work.
Online Works: Please read details.
Computer Programs: One copy of identifying portions of the program (first 25 and last 25 pages of source code) reproduced in a visually perceptible form, together with the page containing the copyright notice, For details please see Circular 61, Copyright Registration for Computer Programs.
Databases: Please see Circular 65, Copyright Registration for Automated Databases.
Secure Tests: Please see Circular 64, Copyright Registration for Secure Tests.