After making your three piles, you should understand that are three possible actions. Obviously, you'll keep the "yes" pile and get rid of the "no" pile. For the "maybe" pile, consider creating what Jesse and Joe call an archive. Jesse says this option is for old clothes that you likely never wear, but which have sentimental value. Jesse and Joe recommend storing archival items in an attic or basement—not in your closet.
This black and yellow dress was a gift from Oprah, and Gayle loves it for sentimental reasons. However, Jesse says it's outdated. It is a quintessential "archive" item.