We check, we double check, and then we check again, but sometimes...no matter how perfect we aspire to be, sometimes mistakes happen. Personally, I blame the computer gremlins. If you ever find a typo (that wasn't included in the original copy, and we do keep them) we will correct it at no charge. This doesn't extend to industry specific terminology, such as medical, that would not be included in a standard American dictionary. Though there are typically several people to proof a website before it goes live, it's always a good idea to double check the copy before you submit it.
Writing For The Web.
Something to keep in mind when writing copy for your website...online, less is more. People read differently online than they do from printed matter such as a magazine or book. Eyes tire more easily when reading words on a screen. Admit it...you're tired of reading this already, aren't you?! Yes, I know you are... Users tend to "skim" more, and are typically distracted more when online.
Best practices dictate using short paragraphs, much like writing for a newspaper. Give your readers' eyes a break with enough "white space." Nothing loses people like a string of run-on sentences with no punctuation. Instead, give them "sound bites" of information to take in. Make each word count, and let it be seen.