Great article about Wikipedia and PR on Ragan.

1. There is a (correctly) cited and verified fact about your brand that happens to be negative or not officially acknowledged. If information about your brand is backed up by what the Wikipedia community considers a reliable and verified source, it must stay. There are clear guidelines on reliable sources here. If there are unverified and unreliable facts, you may have a case of vandalism—which is covered below.

2. You want Wikipedia to sound like your Web site. Wikipedia articles are a collection of cited facts and common-use definitions, so they will differ, understandably, from the About page of your Web site. The lengths of articles vary, based on the amount of public and verified facts and information about the subject. Also, the idea that a brand is “the foremost leader in” or has “the latest and greatest” is opinion, not fact. Any of these “peacock terms” will quickly get you flagged by administrators. (Read more here.)

Now let’s review the acceptable reasons to edit a Wikipedia article. I welcome other examples or opinions below in the comments section.

When editing is acceptable:

Vandalism. Vandalism is any addition, removal or change of content made in a deliberate attempt to compromise the integrity of Wikipedia. This includes obscenities or crude humor, page-blanking (deleting all content on a page) and the insertion of nonsense into articles. If you see vandalism on your page, report it to Wikipedia here.

New information. Maybe you see legitimately important information lacking from an article or you have updated research on a product your company just released. This new information should be added, keeping in mind as with any other Wikipedia edit, that sources for this information must be reliable and verified and that they must pass a gut check. Get smart on the Wikipedia community first, starting with reviewing its Five Pillars.

No article at all. If there is no Wikipedia article about your brand and you wish to create one, you can do so if you have some reliable and verified information to include. Follow this guide on creating your first article, and keep it as short as it needs to be. It might be that the only things verified about your brand are the name and the date it was founded. If so, then that is the only information you should add to the article.

viaWikipedia 101 for PR pros and brand watchdogs | Article | Homepage articles.