Subjects tell the listener and the reader whom or what the sentence is about. The subject is that part of a sentence which names a person, thing, or idea. e.g. Every complete subject contains a simple subject. The simple subject, which is a noun or pronoun, is the most important word in the complete subject.
The USPS considers a postcard to be any single rectangular piece of paper that is at least 3 1/2 inches high by 5 inches long by 0.007 inch thick' and no more than 4-1/4 inches high by 6 inches long by 0.016 inches thick.. The post office considers all papers outside of these dimensions to be letters.
If you're planning to mail a postcard, First-Class Mail gives you the best value for your postage dollars. There is no lower postcard price in USPS Marketing Mail. 0.007 inches? How do I measure that? As a guide, an index card is thick enough. If in doubt, contact a Mailpiece Design Analyst (MDA) at the Post Office near you.