Why are you yelling? Also, their what? Or did you mean "there"?
When people first see another person in the morning they might say "good morning" as it is a polite greeting. This is etiquette. It's the polite way to act within a given situation. What if that situation took place on the Internet? Well, I will tell you about Netiquette—the etiquette of the internet.
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An important thing to remember when online is that you're not like Bilbo Baggins from The Hobbit—your actions are public and global. This means that they can be seen by everyone and will affect them.
In this text sequence, we can see examples of poor Netiquette. The conversation initiator starts off by using an excessive amount of capitals. This is unpleasant to look at so it should be avoided. The respondent decides to correct a grammar mistake. Something that can be helpful but is usually unappreciated. This goes back to knowing your audience but generally avoid it.
Here we can see two other violations of Netiquette. The first one being not staying on topic and the second being self promotion. These should be avoided unless you know your audience is okay with it.
Now that you've graduated Netiquette class, keep one last thing in mind. How would your grandma respond to your actions?
Also, think about the Apollo astronauts. They saw a large portion of the world at once. That is similar to the affect of your online activity--it can affect the world.