A trade paperback can refer to any book that is bound with a heavy paper cover that is generally cheaper than the hardcover but more expensive than the regular paperback version.
In comics, a trade paperback specifically refers to the periodic collections of the regularly published issues, usually capturing one story arcs in the series. These usually span anywhere between 4 and 12 individual issues, and are usually published about two months after the release of the last issue collected by the paperback.
Tradepaperbacks are generally cheaper than hardcover books, but more expensive than mass-market paperbacks.
The shape of a tradepaperback is similar to a hardcover book, as opposed to a mass market paperback, the height of which is approximately the combined width of the a mass-market paperback and a hardcover book.
Tradepaperbacks were once used primarily for special editions, but for many literary titles tradepaperbacks have now replaced regular paperbacks as the format for a book's subsequent release once its hardcover edition has been discontinued.
Traditionally, a tradepaperback will reproduce the stories at the same size as they were originally presented in comic book format; recently, however, certain trades have been published in a smaller, "digest"-sized format, similar in size to a paperback novel.
For many years, tradepaperbacks were mainly used to reprint older comic-book stories that were no longer available to the average reader, when original copies of those stories were scarce and hard to find, and often very expensive when found due to their rarity.
As the tradepaperback versions are usually cheaper than buying the individual comics and presented without any advertisements at all, many comic book fans choose to hold off on purchasing the individual issues and only follow the stories when they come out in trade.