Enormous data breaches were much harder to accomplish in the days before networked electronic databases—that’s why nearly all of our selections for the worst security breaches happened since 2005. If you want to make your enterprise impervious to attack, don’t process credit card payments and don’t collect e-mail addresses. Okay, we admit that’s a bit impractical, but at the very least, encrypt that data. All though all of the companies on this list suffered damage to their brands when their names were publicized in conjunction with some of the largest data breaches ever recorded, fewer suffered actual monetary losses, which offers some consolation. Two of the keys to protecting an enterprise against data theft seem to be (besides, as mentioned, encryption) reliable and trustworthy vendors and partners, and savvy customers and clients who know how to create strong login credentials and resist phishing attacks.