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 USPS dictates size standards for mail in the United States based on the requirements of its automatic mail-sorting equipment. The minimum postcard size is 3.5 inches by 5 inches. The maximum postcard size is 4.25 inches by 6 inches. The USPS also requires the postcard be between 0.007 inch and 0.016 inch thick. Postcards under the minimum size or weight are not mailable.