How is the connection to a PostgreSQL database established?

Connecting to a PostgreSQL database in Python is usually done using the psycopg2 or asyncpg library for asynchronous access.

Example of connection using psycopg2:

import psycopg2

try:
    connection = psycopg2.connect(
        dbname="your_db_name",
        user="your_username",
        password="your_password",
        host="localhost",
        port="5432"
    )
    cursor = connection.cursor()
    cursor.execute('SELECT version();')
    db_version = cursor.fetchone()
    print(f"Connected to - {db_version}")
except Exception as error:
    print(f"Error connecting to PostgreSQL: {error}")
finally:
    if connection:
        cursor.close()
        connection.close()

This example creates a connection to the database, executes a simple query, and closes the connection.