An unreliable software application is a program that frequently crashes, produces errors, or fails to perform its intended functions. Users may experience unexpected behavior, such as data loss or incorrect outputs, which can hinder productivity and lead to frustration. These applications often lack proper testing and quality assurance, making them prone to bugs and vulnerabilities. In contrast to reliable software, which consistently meets user expectations, unreliable applications can compromise user trust and may require frequent updates or patches to address issues.