Usability testing involves having people complete tasks while thinking aloud to provide insight into their thought processes. It can be done using paper prototypes, websites, or existing sites. Benefits for designers include uncovering unexpected issues, testing assumptions, and getting stakeholder buy-in. Benefits for site owners are fixing problems early when cheaper, improving customer satisfaction, and increasing conversion rates. Guerilla or informal testing is quick, inexpensive, and provides qualitative insights that can immediately feed back into the design process. It involves recruiting your own test subjects and moderating the sessions yourself.