Qfyilyi

First of all, I am not good at English but I have to mention this. İt's annoying me. Please excuse my usage of language.

''It is nice to see you.''

What is the subject of this sentence? What is the thing that is nice? Obviously, it is ''to see''. To see you is nice. But according to the sentence above ''it'' is subject of this sentence. But according to the reasoning, to see is the subject, too. In the final analysis, we can say that we have two words that have the same meaning. As long as two things have the same meaning we can use the one instead of the other one. Therefore, if ''it'' is the same thing with ''to see'' then we can say that to see is nice to see you.

Or let me ask you this: Why do you use such a structure? And what do you think about it?

Why do you use such a structure?

To speak always in infinitives would be awkward!

The it in It is nice to see you is just a pronoun that takes the place of the thing being described, which is the experience to see you. The thing that a pronoun stands for is called its antecedent, and even though ante means "before," sometimes the pronoun is actually used before the antecedent. Sometimes the antecedent is implied instead of stated implicitly, especially when the meaning is commonly understood:

It is raining.

Here the it means "the weather" or "the current state of things outside." (This isn't limited to English -- in French one would say il pleut for "it's raining," where the il is again a pronoun.)

So the it in it is nice to see you is similarly a placeholder for something that will be explained shortly ("to see you"), and using it makes it possible to invert the order of the expression. That puts the emphasis on the description of the experience ("nice") instead of the thing being described. If you hear someone say that phrase, you might notice that they also put some audible emphasis on "nice"... it's natural to say (where boldface indicates emphasis):

It's nice to see you.

but strange to say:

It's nice to see you.

This is a tricky bit of grammar most native speakers do not think about. Using the "it" first creates a void of meaning in the grammatical subject of the sentence. This causes focus to slip to the predicate for meaning. In your example, the first words that have meaning are "is nice". That is the initial impact of the sentence, its main emphasis.

Before we even know what the specific situation is, we know that "it is nice". This is an ideal way of phrasing things if you want to convey an emotional state or response quickly and clearly to somebody, and the context is either heavily implied or less important than conveying your emotions.

You could rephrase this sentence as

To see you is nice.

Or maybe

Seeing you is nice.

Without losing any meaning at all, but the emotional emphasis is less immediate. Often in English precedence and immediacy is key, and people rush to get the most essential info out as early as possible.