pgAdmin is a popular open-source administration and development platform for managing PostgreSQL databases. It provides a user-friendly interface that allows users to create, modify, and manage database objects such as tables, views, and indexes. With pgAdmin, users can execute SQL queries, visualize data, and perform routine database maintenance tasks. It supports various features like data import/export, backup and restore, and user management, making it a valuable tool for both beginners and experienced database administrators.