Postgres.js is a JavaScript library for interfacing with PostgreSQL databases, allowing developers to perform common database operations with simplicity and flexibility. It increases efficiency, streamlines error handling, and reduces code complexity by providing a lean and fast design, detailed error objects, and direct SQL query execution in JavaScript code. Postgres.js can be used in various real-world scenarios, such as querying data, inserting/updating/deleting records, and creating/altering database objects. To get started with Postgres.js, developers need to set up a local PostgreSQL instance, install the library, and connect it to their application using the `postgres` function. The library supports transactions, which enable atomicity for DML statements. With Postgres.js, developers can build scalable applications quickly, reducing the complexity of database operations and promoting efficient development workflows.