When we talk to our relatives, friends and children we usually address them using their first name.

Hello Peter. How’re you?
Hi James. What’s up?

In a more formal style, we address people using their title and surname.

Good morning, Mrs. Sullivan.

We do not usually address people using both their first name and surname. For example, we do not usually say Hello Vijay Menon.

Titles like Mr. Mrs. and Miss are not usually used alone. However, the title Doctor can be used alone.

Doctor, I’ve got a problem.

But we do not usually say Hey Mr. you are standing on my feet.

Instead you can say: Excuse me, you’re standing on my feet.

Mrs. is used to address married women. Miss is used to address unmarried women. If you do not know whether a woman is married or not, you can use the title Ms. to address her.

The title Professor is used only for certain very senior university teachers.

In English, the titles sir and madam are very common. Letters to strangers often begin Dear Sir and Dear Madam. Note the capital letters. Also note that the word Dear commonly used in salutations does not indicate any level of affection or intimacy. It is merely a polite way of starting a letter.