E-book lending is a practice in which access to already-purchased downloads or online reads of e-books is made available on a time-limited basis to others. It works around the digital rights management built into online-store-published e-books by limiting access to a purchased e-book file to the borrower, resulting in loss of access to the file by the purchaser for the duration of the borrowing period. In December 2010, Amazon introduced the ability for Kindle users to lend ebooks to friends for a 14-day period. However, not all books support lending.