MySQL is a popular open-source relational database management system (RDBMS) that allows you to store, organize, and retrieve data. It is commonly used for web applications, and is the default choice for many Content Management Systems (CMS) such as WordPress, Joomla, and Drupal. MySQL uses Structured Query Language (SQL) to communicate with the database, making it easy to interact with and manipulate data. MySQL can be installed on various platforms including Windows, Linux, and Mac OS X, and can be integrated with a wide range of programming languages such as PHP, Python, and Java. With its scalability, reliability, and ease of use, MySQL is a popular choice for businesses of all sizes, from small startups to large enterprises.