The \\"C\\" stands for \\"currency,\\" which refers to how current the information on the site is. If a site has not been updated for quite a while, it may indicate that the information is no longer valid. Depending on the topic of your research, that could mean you shouldn\\'t use the site as a source. Currency is most important in scientific areas or current events. While literary sites do not necessarily call for the most recent information, using old information about space travel, for example, could result in erroneous information.