<em>342 words is a little long for an IELTS written exercise - I think 300 is the maximum. </em> I'll split it into two parts.
Is The Internet The most Important Invention Ever?
Many people in the world claim that Internet is one of the most important inventions ever, and there are several reasons to believe it. Other people contend that internet is more dangerous that useful. Indeed both ideas have strong arguments in their favor. As far as I’m concerned internet is one of the most important inventions, and but it has both advantages and disadvantages. <em>(just suggestions, not exactly errors)</em>
There are three good reasons for saying that internet is an important invention. First, internet is the best source of publicly accessible information and no one can dispute that. Second, it has powerful search engines, what which enables<em> ('engines' is plural)</em> you to find information more quickly. Last, but not least important, internet is a good and modern means of communication.
On the whole <em>(this is used for summary conclusion, not for specific arguments)</em> Some may<em> (they do!) </em>argue that, even though/although internet is a good source of information, there is also a lot of wrong information as well as harmful material, for instance pornography and violence. Another disadvantage of internet is shiny that distractions are in everywhere; it’s easy to waste your time on the Internet. And Finally, communication through Internet disconnects/isolates us from those physically around us.
<em>Pretty good Antonio!</em>
Is The Internet The most Important Invention Ever?
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Let’s imagine, for instance, a family gathering , in where pre-teens are using their mobile phones all the time, instead of live socialising together with their relatives. That situation could be considered irritating/enfuriating disgusting, but not only it could be disgusting, but also<em></em>(you already said 'but not only') it could atually hurt relationships. This might be illustrated with a group of friends eating together; the a common situation/normally you would be to see them, laughing, swapping stories or only just catching up. However, nowadays it is very common more usual to see this such a group of friends having the phone in hand or on table, chatting with other people; this event could reduce the level of empathy and understanding in the face to face conversation <em>(this is repetitive, you had already said it). </em>
In conclusion Internet is an excellent source of information, but we must check its legitimacy. It’s also a good idea to use the internet in order to stay in contact with people, since it’s easy and convenient. However we shouldn’t allow internet to replace physical relationships.