The word Nippon is commonly found on the underside base of a litany of items including but not limited to teapots, plates, cups, vases, and other ceramic objects. Nippon was a mark that had a lot to do with the American rise of the wealthy class and the Gilded Age of the latter part of the 1800s and early 1900s.
Simply, Nippon means Japan and while the "Nippon" mark served its purpose to comply with the Mc Kinley Tariff Act of 1891 for the next thirty years, Customs Officials decided, in 1921, that any piece imported from Japan should be marked "Japan" and not marked "Nippon." So, the "Nippon" mark was no longer the recognizable mark used for these items.
For porcelain collectors, this makes dating your piece really easy.
If you know any dates for a backstamp not shown here, feel free to leave the information in the comments. UPDATE 1/4/12: We’ve added more backstamps to this post! The script used in “Hand Painted” is also a bit different.
UPDATE 2/20/12: Even more backstamps have been added to the list!
We cannot stress enough that this is NOT a complete list.