Nowadays the internet is used for serious stuff as you guys stated above. Before, the internet used to be for tech-geeks, and people who had interest in going "online" and viewing pages stored not on your hardrive, but on other peoples. But, as the internet evolved, chat systems and messengers came in. Then came the pouring teens. Talking for free, without the hassle of having a phone charged, or only talking during certain times to get calls for free, the internet was a reliable, and relatively cheep way to communicate with friends and family in a no-hassle kind of way. Then, as it kept on evolving, so did eMail. Now, you can send pictures and videos of yourself and/or your family, to lets say a family member 100s of miles away from you.
Then, the new age. The light of the internet was seen from teens to young adults. Torrents. The internet can be used to store files and allow them to be publicly downloaded to you harddrive. So why not 'share' files? Thats when P2P networks came into play. LimeWire, KaZaa, BitTorrent, Azureus just to name a few. You could get retail things, for free! Then, teens discovered that websites can offer pornography. Meaning, the internet is not only a reliable tool used to enhance your knowledge, but something that can distort your mind into something, that you may not actually be.
And as teens start using email and messenger to converse their thoughts and opinions, grammer is usually not implied. So, mistaken meanings can lead to the 'real world' and thus affect the relationship you had with the person. Also, emails can be sent anonymously to people you hate, called 'hate mail'. In my opinion, I take "the internet" seriously, but i take most of the people in not, "not seriously".