a noun 'letter' can refer to a physical object sent in the mail or to an image contained within a book. It also can mean a letter of alphabet.
a 'letter' can stand alone as its own object, or it can refer to a physical representation of an idea, a charm, or a thought. A 'letter' can also be used as the subject or object of a sentence, either in its singular or plural form. 'Letter' can also refer to the container of a message or set of ideas, such as a letter from the President or a statement from a public figure.
1. I received a letter from my grandpa in the mail.
2. Last night I wrote a heartfelt letter to my friend.
3. My professor gave us an important letter regarding class registration.
when referring to a physical representation of an idea, be sure to specify what it represents. For example, instead of saying simply 'I sent the letter,' say 'I sent the letter of apology.' When using 'letter' as the subject or object of a sentence, ensure the sentence is properly formed and the verb agrees in number with letter. Be aware of context when using 'letter,' as its meaning may change depending onit. For example, a letter from the President is different from a letter in a book.