Strategy guides are instruction books that contain hints or complete solutions to specific video games. The line between strategy guides and walkthroughs is somewhat blurred, with the former often containing or being written around the latter. Strategy guides are often published in print, both in book form and also as articles within video game magazines. In cases of exceptionally popular game titles, guides may be sold through more mainstream publication channels, such as bookstores or even newsstands. Some publishers also sell E-Book versions on their websites.