MySQL is a widely-used open-source relational database management system (RDBMS) known for its reliability, speed, and ease of use. It supports structured query language (SQL) and is highly efficient for managing structured data in web applications, offering features like data security, ACID compliance, and support for transactions. MySQL is commonly used in various applications, from small-scale projects to large-scale enterprise systems, particularly for powering dynamic websites and applications. Its scalability and integration with platforms like WordPress, Drupal, and major cloud providers make it a popular choice for database management.