Web literacy is a necessary skill to develop for finding accurate information online. The techniques for finding proper sources online are different than those for print, but just as important.
Web literacy begins with reading the web address. Addresses ending with .gov and .mil are government sites, so typically reliable. Colleges and universities use .edu, but watch out for personal sites hosted by the college, usually denoted by a ~ or % and a personal name. Nonprofits were once the only organizations allowed to use the .org addresses, but that restriction has been lifted.
Beyond the address, there are several criteria usable to evaluate content on a website. Penn Libraries use the ABCs of Web Literacy, which looks at the authority of the author; the accuracy of the information and if it can be verified; the bias of the author; how current the information is; and how much coverage the website gives based on the users needs. Other methods will have different criteria but will focus on most of the same issues.
Web credibility is related to web literacy; it is concerned with what makes a website appear credible to the viewer. Stanford University has established 10 guidelines for Web Credibility. These can be used for determining if a website appears credible, but aren't a guarantee.
The Rapid City Libraries maintain a more comprehensive page on Web Literacy, along with information on copyright and citing sources.