'ing form

DiddyI want to ask you when to use ' form and when to write the whole word?

And by the way what is the ' form called?

Are you talking about the present participle, such as going? Your post is too vague to elicit much of an answer. If this is a good staring point, add to it, and people will be able to help.

I am talking about the diffrence between

Do not.

And

Don't.

But not only that example I am talking in general. That form. What is it called? And when to use the first one and when to use the second one?

I hope it is making sense now, if not please tell me and I will try make it more understable.

Ah! A contraction.

You are talking about contractions, in which the ' is used to represent the letter that are left out.

Do not = don't

It is = It's

I am = I'm

You can substitute a contraction in almost all cases in which you'd use the regular words. Some people consider them informal, but I personally find that leaving all of them them out makes writi

so you prefer to use contraction?

I think (as not native speaker) that contractions should be use when you talk and the whole word shoud be written when you are writing.

Americans, at least, find contractions to be more natural. I tend to use them when writing.

Use them if you want to write more informally, Don't if you want to write very formally.

But my english teacher tells me to not use them when writting.

And by the way what is the diffrence between writing, informally and formally?

If you are writing to a friend, you write informally. If you are writing a paper for your work or a paper for school, you write more formally. If you are writing a thank you note to an older person, you probably write more formally. If you are sending an e-mail, you are probably writing informally, unless it's to the president of your company - in which case you'd write very formally.

Bu

Would it sound odd to use the whole form of a word when speaking?

i.e.

I do not know where it is.

And furthermore I have read books in which the Author use the whole form of a word unless when using diagolue of couse.

Unless you really wanted to emphasize one of the words (e.g., "No, I do NOT know where it is!") you would not sound natural. That doesn't mean you'd sound wrong, but you'd sound like someone who doesn't speak English like a native. In science fiction movies, the robots rarely use contractions, for example.

Authors will have their own style. For now, do as your teacher tells you and when

Just to clarify a bit on Grammer Geek's response: In conversation, contractions are always used unless a person wants to emphasize a particular word.