Today, Federal Reserve banks will begin distributing the redesigned $5
bills to customer banks, which will then distribute them to businesses
and consumers.  The new $5 bill designs will circulate first in the
U.S. and gradually spread to other countries.  Both the new $5 bills and the
older-design $5 bills will remain in circulation but it's easy to tell them apart because the new fives have a huge purple "5" in the corner. They new bills are pretty ugly, actually.   

The new $5 bill incorporates state-of-the-art
security features.  Hold the bill to the light to check for these features:

Watermarks: There are now two watermarks on the redesigned $5 bill.  A large number "5" watermark is located in a blank space to the right of the portrait replacing the previous watermark portrait of President Lincoln found on the older-design $5 bills.   A second watermark — a column of three smaller “5”s — has been added to the new $5 bill design and is positioned to the left of the portrait.

Security Thread: The embedded security thread runs vertically and is now located to the right of the portrait on the redesigned $5 bill.  The letters "USA" followed by the number "5" in an alternating pattern are visible along the thread from both sides of the bill.  The thread glows blue when held under ultraviolet light.