Wikipedia:Most common Wikipedia faux pas

There are a number of faux pas that some new contributors make sometimes, here's a list for your convenience:

Some important things to try to avoid when working on Wikipedia:

1. Worrying too much that you're going to mess things up. You probably will a little; everybody does, to some extent. But then someone else will probably clean up after you. The community encourages participants to be bold in updating pages.
2. Treating Wikipedia as a dictionary. While article "stubs" are perfectly fine, and a good stub might have only a little more information than a dictionary definition, we aren't engaged in defining common words, or compiling a dictionary. And note that defining professional and academic jargon essential to understanding a larger article is not only appropriate, it's encouraged. For more in this vein, see Wikipedia is not a dictionary and what Wikipedia is not. If you want to work on a wiki dictionary, check out Wiktionary (http://wiktionary.wikipedia.org)!
3. Capitalizing titles of articles. It's unnecessary to capitalize the "g" in "French grammar". The link should look like this: French grammar. Otherwise, Capitalizing Everything for which there is a link, Looks Very Strange. (See the naming conventions for more information on how to name articles).
4. Duplicating articles. Do a search before creating a new article -- you may find that one already exists (of course, you can add to this one!). In particular, bear in mind that most articles have titles in the singular, eg "tree", not "trees".
5. Deleting useful content. It's considered impolite and counter-productive to simply delete content that is useful just because it is somewhat biased (why not just remove the bias?) or because it's poorly copyedited (why not do the necessary copyediting?). Except in the very most obvious of cases, deleting anything over, say, a few sentences demands some words of justification on a talk page. A good principle is never to reduce the overall amount of useful content in an article.
6. Treating Wikipedia as a chat forum. On talk pages, it is all too easy to get involved in emotional, partisan debates about various topics. This is a bad thing unless it results in an improved article, which it often doesn't. There are many other places online where you can engage in debate and to try to persuade other people of your views. That's really not appropriate on Wikipedia, because the project focuses on the task of creating an encyclopedia. Please see What Wikipedia is not.
7. Thinking that there is an "author" of any given article you read. A common misconception of new arrivals to Wikipedia is that there are single authors of articles. This leads people to issue critiques on Talk: pages when they could just as easily make changes to articles themselves. The fact of the matter though is that no article here has just one official author, even if only one person has worked on it. Anyone can work on any article, and if you see a problem with an article, you are encouraged to fix it. Don't bother with the Talk: page unless politeness demands you explain what you've changed, or that you ask a question first. For more information, see Be bold in updating pages and Talk page.
8. Adopting a combative stance. Some new people immediately see that there is a special community of people here committed to working together toward friendly consensus. Others make the mistake of treating disputes on Wikipedia as on a par with Usenet-like flame wars. Most old hands want to spend as little as possible time in nasty, competitive disputes. That isn't what Wikipedia is about. There are acrimonious disputes, even among the old hands. We aren't perfect. But it does seem safe to say that most of us aren't here for that, and we are embarrassed and frustrated when it reaches that level. We're here to write an encyclopedia. For that, some amount of Wikipetiquette (if you will) is required. See also Staying cool when the editing gets hot.
9. Judging and trying to change Wikipedia before you understand it. Realize that Wikipedia is a work in progress, and a lot of intelligent people are working on it and care about it. And they've thought a lot about it. Some people arrive on the scene and, failing to understand how and why Wikipedia works, start lobbying for greater controls, or they judge the project based on new, incomplete, and otherwise inadequate articles. Generally speaking, if you want to be comfortable here, please tolerate a little (temporary) imperfection. Bear in mind that a community of contributors is working on this thing together, so it constantly improves. See Wikipedia and Wikipedia FAQ for more information on the project in general. See replies to common objections for more.

This list is limited to the most common and important Wikipedia faux pas. For other guidelines, see Policies and guidelines.