A .psql file is a plain text file containing SQL queries designed to be executed against a PostgreSQL database. These files are essentially scripts that can be run using the psql command-line utility, which is the interactive terminal for working with PostgreSQL. The scripts can contain a single SQL statement or a series of statements, including commands to create tables, insert data, update records, delete entries, and perform complex queries. They often include comments to explain the purpose of different sections of the script. PSQL files are commonly used for database initialization, schema updates, data migration, and running batch processes. They provide a convenient way to automate database tasks and ensure consistency across different environments. The psql utility interprets the SQL commands within the file and sends them to the PostgreSQL server for execution. Error handling and transaction management can also be incorporated into the script to ensure data integrity. These files are crucial for database administrators and developers who work with PostgreSQL databases.