grammar
a system of understanding a language using proper sentence structure, uses of words and their functions in a sentence, spelling, and other things. 
Grammar is sometimes thought of as obsolete because it seems that no one cares to use it anymore. However, there is nothing wrong with abandoning grammar online because that is it what it is meant for! All of you who are making fun of people who use abbreviations on the internet are stupid, because that is the point, you are supposed to be able to say things quicker, even if it means spelling "for" as 4! 