Perhaps something that not everyone knows is that editing has more than one facet. Although not exactly a diamond in itself, good editing may take your story from a diamond in the rough to a priceless piece of literature.
Editing at its most basic level is known as proofreading. It is looking over a document for simple grammatical errors. Spelling, punctuation, word order or word agreement (too instead of to) are all things a proofreader looks at. It's often done after a more intensive edit and is usually the final check before submittal.
Substantive editing (also known as developmental editing and comprehensive editing) is a much more thorough overhaul. Changes may be made for improvement of clarity, organization, and overall structure. The intended purpose of the article is always on the forefront of the editor's mind, and the readers are a huge consideration. The editor will decide whether the language is relevant and appropriate, and if the article will make sense to them. It may require a partial or total rewrite of an article. A substantive edit will often cost more because there is usually much more work involved.
Proofreading and substantive editing are both important for their own reasons. Proofreading is important for the simple reason that it's the little mistakes we make that ruin our credibility as writers. It's those very mistakes that say if a writer doesn't care enough about his piece to fix the small stuff, then why should anyone else? The unfortunate result is that the best story you ever wrote ends up in the circular file.
Substantive editing is equally important because if an article does not read well, you will lose the reader's interest. If you lose the reader's interest, then once again, credibility is lost.
So if you want to make a career of writing, or if you want to write something that people will keep on reading, then do yourself a favor and take the extra time to turn your article into a sparkling diamond.