Dapper is a lightweight, open-source library used in .NET applications for data access. It simplifies the process of interacting with databases by allowing developers to execute SQL queries and map the results to .NET objects easily. This makes it a popular choice for developers who want to work with databases without the overhead of more complex frameworks. One of the key features of Dapper is its performance. It is designed to be fast and efficient, making it suitable for applications that require quick data retrieval. Additionally, Dapper supports various database systems, including SQL Server, MySQL, and PostgreSQL, providing flexibility for developers working in different environments.