The Internet is now an integral part of the everyday lives of a majority of people. Web users are becoming increasingly skeptical of the information and services offered online. They are demanding web sites that offer credible information. This study focused on what features of web sites affect the perception of web credibility. For this purpose, I took the responses from 648 people and extracted 49 factors that affect web credibility. I placed the individual factors - the specific questions asked in the survey - into one of four categories: expertise, trustworthiness, ads and other and calculated the means for each of the 49 factors. As a result, 29 out of 49 factors increase the perceptions of credibility and 20 factors decrease the web credibility. Sites with frequently update, the credentials of authors, strict content guides, search capabilities, clear connections to the real world fared good in credibility. Technical problems such as broken links, site sown, or typographical errors were rated the most negative on this scale. On the other end of the scale, a domain name that ends in '.org' or '.or.kr' caused little change in perception of credibility.