Wikipedia: Scientific American (informally abbreviated to SciAm) is a popular science magazine, one of the oldest and most prestigious, published since August 28, 1845, making it the oldest continuously published magazine in the United States. It brings articles about new and innovative research to the amateur and lay audience. Scientific American had a monthly circulation of roughly 555,000 in the United States and 90,000 internationally as of December 2005. It is not a refereed scientific journal, such as Nature; rather, it is a forum where scientific theories and discoveries are explained to a broader audience. In the past scientists interested in fields outside their own areas of expertise made up the magazine's target audience. Now, however, the publication is aimed at educated general readers who are interested in scientific issues. The magazine American Scientist covers similar ground but at a level more suitable for the professional science audience, similar to the older style of Scientific American.