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.
The only cards that are actually classified by USPS as postcards are cards (not envelopes) that: 1  are rectangular in shape; and, 2  are at least 3Â½ inches tall but no more than 4Â¼ inches tall; and, 3  are at least 5 inches wide but no more than 6 inches wide; and, 4  are at least 0.007 inches thick but no more than 0.016 inches thick.