The Internet certainly connects the world more than we were twenty years ago. We get instant news, instant entertainment, and instant feedback. In many cases this instant gratification can be just as much a bad thing as it can be a good thing.
One of the problems with the Internet is the online disinhibition effect. The online disinhibition effect happens when the inhibitions one would normally demonstrate in the real world are loosened. This loss of inhibitions often causes people to say and do things on the Internet that may be embarrassing, hurtful, or just completely out of character; stuff that they wouldn't do or say in public.
There are many reason that this effect can happen and many degrees, but what is important is that you remember that at the other side of the screen is a real person with real feelings. Everyone is entitled to their opinions and their beliefs, but when you choose to voice yours in a public forum like Twitter, Facebook (Yes, Facebook. Even though you choose who sees your comments it is still a social network.), or blogs, be prepared for others to have a difference of opinion. If you are not up to someone challenging you, then simply don't post. The purpose of these types of social media is in fact to be social, to start a conversation.
I am a librarian which means I fully support freedom of speech and a person's right to information. However, I draw the line at talk that is discriminatory and hateful. Thankfully many social media outlets agree and have policies in place for just such a thing. So remember before you post have a little civility and think before you type or you just might find yourself booted from the network.