Spelling

Spelling is the means by which letters are combined to make words that others will recognize. This, along with punctuation and grammar, is the basis for all written communication. Without standardization, all is chaos.
It must be noted that what constitutes a word in the above definition is not negotiable. If it's in the Oxford English Dictionary, it's a word. If it's not in there, it's not a word. Unless it's a name. Or you're writing in a language other than English, of course.
Often, bad spelling is caused by inaccurate typing and/or a simple inability to spell, something that many people unfortunately suffer from. But this is fixable. It is when someone simply does not bother to even reread their work or have it beta'd that it becomes unreadable. Bad spelling should never see the light of day; it should be buried in drafts.
==Links==
The Oxford English Dictionary Online is available by subscription. However, if you'd rather not subscribe, there are many other places to look up words online. Some favorites include the following:
*Merriam-Webster Online
*Wiktionary
*Dictionary.com
*Common Errors in English Usage by Paul Brians
Category:Terminology
Category:Flaws