Editing (copyediting) and proofreading are critical to the production of a quality book. Books with typographical, grammatical, spelling, and punctuation errors simply look unprofessional. Any serious author must ensure his or her book has been thoroughly proofread and edited by an experienced editor. It is important to note here that using electronic applications such as “Spell Check” is no substitute for a good, HUMAN editor with the knowledge, experience, and resources necessary to recognize and fix all sorts of errors in your text.
Most traditional publishing companies have such editors on staff. However, this is not a guarantee with self-publishing companies. Many of these “Vanity Press” companies will claim to edit your work, but they use the term quite loosely. In reality, if they do any editing-related work at all, it will likely involve nothing more than running your electronic file through one of the aforementioned Spell Check applications, which will pick up only blatant misspellings and a few types of grammatical and punctuation errors.