It and This are two words in the English language that are often confused in terms of their meaning. They are actually two different words with different meanings. The word ‘it’ is the third person singular pronoun. On the other hand the word ‘this’ is a demonstrative pronoun. This is the main difference between the two words it and this.
The word ‘it’ is normally used to begin sentences that lay emphasis on a subject or an idea as in the sentence ‘It is important to follow the rules and regulations.’ In this sentence the word ‘it’ is used in the sense of laying emphasis on an idea. On the other hand the demonstrative pronoun is used to refer something to somebody as in the sentence ‘This is the book I mentioned in my lecture’. In this sentence the word ‘this’ is used in a bid to demonstrate or introduce the book to someone by somebody. This is also an important difference between the two words ‘it’ and ‘this’.
Sometimes the word ‘it’ is used in the beginning of assertive sentences as in the sentence ‘It is raining heavily now’. You can see that this assertive sentence begins with the word ‘it’. One of the primary uses of ‘it’ is its usage as the third person singular form like the third person pronouns ‘he’ and ‘she’. Observe the two sentences
1. It shines very well
2. It roars loudly.
In both the sentences the word ‘it’ is used as the third person singular form. In the first sentence the pronoun ‘it’ refers to ‘the Sun’ and in the second sentence the third person singular form refers to ‘a lion’. Sometimes the demonstrative pronoun ‘this’ is used at the end of the sentence as in ‘I know this’.
This and It are two words that are definitely used with some difference between them. The word ‘this’ is used as a demonstrative pronoun whereas the word ‘it’ is used as a personal pronoun.
The word ‘this’ is used to demonstrate a noun that has already been uttered or used in a sentence. Look at the sentences
1. This looks a good one
2. I am ready to buy this....