|This page in a nutshell: Improve pages wherever you can, and do not worry about leaving them imperfect. Preserve the value that others add, even if they "did it wrong" (try to fix it rather than delete it).|
Wikipedia is the product of millions of editors' contributions, each one bringing something different to the table, whether it be: researching skills, technical expertise, writing prowess or tidbits of information, but most importantly a willingness to help. Even the best articles should not be considered complete, as each new editor can offer new insights on how to enhance and improve the content in it at any time.
Wikipedia is here to provide summaries of accepted knowledge to the public, as described in WP:NOT; generally speaking, the more accepted knowledge it can provide (subject to certain defined limitations on its scope), the better it is. Please boldly add content summarizing accepted knowledge to Wikipedia, either by creating new articles or adding to existing articles, and exercise particular caution when considering removing sourced content. However, it is Wikipedia policy that information in Wikipedia should be verifiable and must not be original research. You are invited to show that content is verifiable by referencing reliable sources. Unsourced content may be challenged and removed, because on Wikipedia a lack of content is better than misleading or false content—Wikipedia's reputation as an encyclopedia depends on the content in articles being verifiable and reliable. To avoid such challenges, the best practice is to provide an "inline citation" at the time the content is added (see: WP:Citing sources for instructions on how to do this, or ask for assistance on the article talk page).
Although reliable sources are required, when developing articles on the basis of sources, avoid copying or closely paraphrasing a copyrighted source. Wikipedia respects others' copyright. You should read the source, understand it, and then express what it says in your own words.
Another way editors can improve an article is by finding a source for existing unsourced content. This is especially true if you come across statements that are potentially controversial. You do not need to be the person who added the content to add a source and citation for it.
Perfection is not required: Wikipedia is a work in progress. Collaborative editing means that incomplete or poorly written first drafts can evolve over time into excellent articles. Even poor articles, if they can be improved, are welcome. For instance, one person may start an article with an overview of a subject or a few random facts. Another may help standardize the article's formatting or have additional facts and figures or a graphic to add. Yet another may bring better balance to the views represented in the article and perform fact-checking and sourcing to existing content. At any point during this process, the article may become disorganized or contain substandard writing.
Further information: Wikipedia:Biographies of living persons
Although perfection is not required, extra care should be taken on articles that mention living persons. Contentious material about living persons (or, in some cases, recently deceased) that is unsourced or poorly sourced—whether the material is negative, positive, neutral, or just questionable—should either be verified immediately, with one or more reliable sources and presented in a neutral manner without undue weight, or be removed immediately, without waiting for discussion.
Fix problems if you can, flag or remove them if you can't. Preserve appropriate content. As long as any facts or ideas would belong in an encyclopedia, they should be retained in Wikipedia. Wikipedia is an encyclopedia.
Likewise, as long as any of the facts or ideas added to an article would belong in the "finished" article, they should be retained if they meet the three article content retention policies: Neutral point of view (which does not mean no point of view), Verifiability, and No original research.
Instead of removing article content that is poorly presented, consider cleaning up the writing, formatting or sourcing on the spot, or tagging it as necessary. If you think an article needs to be rewritten or changed substantially, go ahead and do so, but it is best to leave a comment about why you made the changes on the article's talk page. The editing process tends to guide articles through ever-higher levels of quality over time. Great Wikipedia articles can come from a succession of editors' efforts.
Instead of removing content from an article, consider:
Otherwise, if you think the content could provide the seed of a new sub-article, or if you are just unsure about removing it from the project entirely, consider copying the information to the article's talk page for further discussion. If you think the content might find a better home elsewhere, consider moving the content to a talk page of any article you think might be more relevant, so that editors there can decide how it might be properly included in our encyclopedia.
Several of our core policies discuss situations when it might be more appropriate to remove information from an article rather than preserve it. Wikipedia:Verifiability discusses handling unsourced and contentious material; Wikipedia:No original research discusses the need to remove original research; What Wikipedia is not describes material that is fundamentally inappropriate for Wikipedia; and WP:UNDUE discusses how to balance material that gives undue weight to a particular viewpoint, which might include removal of trivia, tiny minority viewpoints, or material that cannot be supported with high-quality sources. Also, redundancy within an article should be kept to a minimum (excepting the lead, which is meant to be a summary of the entire article, and so is intentionally duplicative).
Libel, nonsense, and vandalism should be completely removed, as should material that violates copyright and material for which no reliable source that supports it has ever been published.
Special care needs to be taken with biographies of living people, especially when it comes to handling unsourced or poorly sourced claims about the subject. Editors working on such articles need to know and understand the extra restrictions that are laid out at Wikipedia:Biographies of living persons.
Be bold in updating articles, especially for minor changes, fixing problems, and changes that you believe are unlikely to be controversial. Previous authors do not need to be consulted before making changes. Nobody owns articles, so if you see an improvement you can make, make it.
If you think the edit might be controversial then a better course of action may be to first make a proposal on the talk page. Bold editing does not excuse edits against existing consensus, edits in violation of core policies, such as Neutral point of view and Verifiability, or edits designed to create a fait accompli, where actions are justified by the fact they have already been carried out.
If someone indicates disagreement with your bold edit by reverting it or contesting it in a talk page discussion, consider your options and respond appropriately. The "BOLD, revert, discuss cycle" (BRD) is often used when a contentious edit has been reverted.
Be helpful: explain your changes. When you edit an article, the more radical or controversial the change, the greater the need to explain it. Be sure to leave a comment about why you made the change. Try to use an appropriate edit summary. For larger or more significant changes, the edit summary may not give you enough space to fully explain the edit; in this case, you may leave a note on the article's talk page as well. Remember too that notes on the talk page are more visible, make misunderstandings less likely and encourage discussion rather than edit warring.
Be cautious about making a major change to an article. Prevent edit warring by discussing such edits first on the article's talk page. One editor's idea of an improvement may be another editor's idea of a desecration. If you choose to be bold, try to justify your change in detail on the article talk page, so as to avoid an edit war. Before making a major change, consider first creating a new draft on a subpage of your own user page and then link to it on the article's talk page so as to facilitate a new discussion.
Further information: Wikipedia:What Wikipedia is not § Wikipedia is not a publisher of original thought
Whether you decide to edit very boldly or discuss carefully on the talk page first, please bear in mind that Wikipedia is not a discussion forum. It is best to concentrate our energies on improving articles rather than debating our personal ideas and beliefs. This is discussed further at Wikipedia:Etiquette.
The Wikipedia:Dispute resolution processes are available if you need help reaching an agreement with other editors.
For guidance on how to edit talk pages see: