Some people advocate that one shouldn't say anything over electronic media that one wouldn't say on prime time t.v. Others believe that no strangers can ever see anything sent to or posted for a specific individual or group of individuals. Neither view is accurate.
"Public" forms of electronic communication, such as web pages and blogs, are the most like broadcasting. Or, for most people, like a small press publishing a book on an obscure topic. Probably only your friends and family will be interested in reading it, and only those you tell about it will even know it exists. But unlike a book, it never goes out of print, it 's available to anyone in the world, and search engines can link to it, so the chances of unintended readers increases.
"Private" forms of electronic communication -- e-mail, texting, chat, personal social network pages, photo sharing pages, news groups, small, private blogs -- are more like talking quietly in a restaurant. For the most part, nobody's listening, but stray bits might be overheard, and nosy people may be able to hear as much of the conversation as they want with a little effort.