User trust is essential for adoption of new technologies but is influenced by psychological factors. Key elements like reliability, usefulness, ease of use and privacy contribute to trust, as well as familiarity and social proof. Cognitive biases also shape trust through emotions and herd behavior. Designers can build trust by making systems transparent, straightforward, approachable and privacy-focused through trial usage and security indicators. Trust is fragile and influenced beyond functionality, so recognizing psychological impacts is important for trustworthy design.