SQL Server Express is a free, lightweight edition of Microsoft SQL Server, ideal for small-to-medium .NET Core 2 web applications. It offers seamless integration with the Microsoft ecosystem, ease of use, and scalability options for future upgrades. With features like reporting services, full-text search, and support for stored procedures, it’s a solid choice for developers. However, its limitations, such as a 10GB database size cap, 1GB RAM limit, and single CPU usage, may hinder large-scale applications. While PostgreSQL offers better performance for high-concurrency workloads, SQL Server Express excels in simplicity and integration, making it suitable for Microsoft-focused projects.