Retro typically refers to culturally outdated trends or fashions, especially between World War II and the 1990s. Retro equals nostalgia -- whether it's a patio chair, a pair of shoes, a car, or a 1950s drive-in restaurant. Baby boomers will enjoy a trip down memory lane at posters.com. Simply type "retro" into the search box and go back in time through the hundreds of retro posters available online.