Ensuring cross-browser compatibility is crucial for web applications before deployment, as different browsers and devices can display varied behaviors. Developers often work on a single browser, leading to issues when the application is accessed via others, necessitating comprehensive testing across major browsers like Internet Explorer, Microsoft Edge, Mozilla Firefox, Google Chrome, and Safari. Internet Explorer, particularly IE 8, presents challenges with modern frameworks and long-running scripts, while Microsoft Edge is more optimized but may still encounter issues with certain styles. Mozilla Firefox, though surpassed by Chrome in developer tools speed, remains popular but may struggle with modern CSS features, requiring vendor-specific prefixes for solutions. Google Chrome is favored for its robust development tools, yet it can face resource validation challenges and image orientation issues. Safari, especially its mobile version, requires distinct testing due to its touch-based interface and features like phishing prevention, which could strip metadata from uploaded files. Regular testing is necessary to adapt to new browser versions to ensure consistent application performance.