What are the different mailing classes available for domestic mail?

The United States Postal Service offers various mailing classes for domestic mail based on urgency and budget. The classes include First-Class Mail, Priority Mail, Priority Mail Express, Retail Ground, Media Mail, Library Mail, and Bound Printed Matter. First-Class Mail is ideal for small packages and envelopes under 13 ounces, with a delivery time of 1-3 business days. Priority Mail is apt for larger, time-sensitive parcels and offers expedited delivery in 1-3 business days. Priority Mail Express guarantees overnight delivery for time-critical items. Retail Ground is for larger and heavier packages and has a longer delivery time. Media Mail and Library Mail are cost-effective options for sending educational materials, books, or media items. Bound Printed Matter is suitable for sending books, catalogs, and advertisements at an affordable rate. Choose the class that best fits your requirements and budget.