Salesforce AppExchange app development involves creating custom applications for Salesforce's marketplace, enabling businesses to extend their CRM functionality. Developers use tools like Salesforce SDKs, Apex, Visualforce, and Lightning Web Components to build apps tailored to specific needs. Key steps include identifying business requirements, designing user-friendly interfaces, integrating with Salesforce data, and ensuring compliance with Salesforce's security and quality standards. Rigorous testing and Salesforce AppExchange Security Review are essential for app approval. These apps empower organizations to enhance productivity, streamline workflows, and address industry-specific challenges, offering scalable and customizable solutions that boost value for developers and end-users.