Code smells are surface indicators that suggest deeper design problems in software systems — they're not bugs, but warning signs of maintainability issues, technical debt, and architectural decay. First coined by Kent Beck and popularized by Martin Fowler, these patterns help developers identify when code needs refactoring. Anti-patterns, by contrast, are common solutions that initially appear reasonable but lead to negative consequences — often arising from organizational pressures, misapplied design patterns, or lack of understanding. The key insight: both code smells and anti-patterns are symptoms, not diseases — they point to underlying structural problems that, if addressed early, prevent systems from becoming unmaintainable legacy codebases.