It seems to me that a large number of people who are currently using the internet to post their various thoughts and ramblings have yet to master some cornerstones of the English language. This page is meant as a primer, or reference to use when posting, in order to avoid looking like a complete idiot. This list is by no means comprehensive, but simply covers some of the more offensive and common mistakes that people make when posting to online discussion forums.

1. The Period. Sentences end with a period. Period. When you are done with a thought, and are about to being another, use a period to differentiate the two.
2. Capital letters. Sentences begin with capital letters. So do names. Always capitalize the letter "I" when speaking of yourself. Do not write in all capitals. It makes it appear as if you are yelling. If you want to add powerful emphasis to a word or two, you can put them in all capitals. For example, DO NOT type your posts in all caps. See??
3. A lot. "A lot" is two words. It means "a whole bunch", or "many". Alot is not a word. While "allot" is a word, it does not mean the same thing as "a lot".
4. Come on. This is an expression commonly used when you are exasperated over someone's lack of agreement with you. Another version is "C'Mon". Though grammatically incorrect, it is commonly viewed as acceptable. However, the word "common" is not the same thing. This word means "every day", or "frequently occurring". "common" is not pronounced the same way as "Come on".
5. Your/You're. These are two different words, with two different meanings. They are not interchangeable. "Your" is used to designate ownership. For example, "Hey, that's your phaser, not mine". You're is a contraction of two words, "you" and "are". Example, "you're a real idiot for having poor grammar".
6. Their/there/they're. These are three different words, and they are not interchangeable. The first one shows possession. "Hey, that's their phaser. It belongs to them". The second one is commonly used to express location. "The phaser is over there, on the table". The third one is a contraction of the two words "they" and "are". Example, "They're going to buy that phaser".
7. Recast. This is what is referred to as a simple verb, in that its conjugation is nearly identical for every article. I recast, you recast, he/she recasts, they recast, etc. There is no such word as "recasted". Even if you put "recast" in the past tense, it does not turn into "recasted".
8. Cast. Same as above. It is never "casted", even in the past tense. You could not have "casted a phaser" last week. However, you could have "cast a phaser" last week. Though this may seem counterintuitive to some, that's only because you don't speak the language properly.
9. To/Too. These are two different words, with two different meanings. They are not interchangeable. The first one, "to", is used as a function word to indicate movement. "I'm going to the convention". The second one means besides, or also. "I sold my phaser and tricorder too".
10. Moot/Mute point. There is no such thing as a "mute point". No such expression exists. It is a "moot point" if it is obsolete, or no longer useful for discussion.