A featured article exemplifies our very best work and features professional standards of writing and presentation. In addition to meeting the requirements for all Wikipedia articles, it has the following attributes.
(a) well-written: its prose is engaging, even brilliant, and of a professional standard;
(b) comprehensive: it neglects no major facts or details and places the subject in context;
(c) factually accurate: claims are verifiable against reliable sources, accurately represent the relevant body of published knowledge, and are supported with specific evidence and external citations; this requires a "References" section in which sources are listed, complemented by inline citations where appropriate;
(a) a lead—a concise lead section that summarizes the topic and prepares the reader for the detail in the subsequent sections;
(b) appropriate structure—a system of hierarchical section headings and a substantial but not overwhelming table of contents; and
(c) consistent citations—where required by Criterion 1c, consistently formatted inline citations using either footnotes (<ref>Smith 2007, p. 1.</ref>) or Harvard referencing (Smith 2007, p. 1) (see citing sources for suggestions on formatting references; for articles with footnotes, the meta:cite format is recommended).
Prose. It features professional standards of writing.
Lead. It has an engaging lead section that introduces the subject, and defines the scope and inclusion criteria of the list.
Comprehensiveness. It comprehensively covers the defined scope, providing a complete set of items where practical, or otherwise at least all of the major items; where appropriate, it has annotations that provide useful and appropriate information about entries.
Structure. It is easy to navigate, and includes—where helpful—section headings and table sort facilities.
The article is well organized and essentially complete, having been reviewed by impartial reviewers from the Opera WikiProject or elsewhere. Good article status is not a requirement for A-Class.
More detailed criteria
Provides a well-written, clear and complete description of the topic, as described in Wikipedia:How to write a great article. It should be of a length suitable for the subject, appropriately structured, and be well referenced by a broad array of reliable sources. Scholarly analysis of the topic is aptly summarised. Inline citations are essential. It should be well illustrated, with no copyright problems, preferably with free media rather than fair use ones, which are only to be used as a last resort.
An A-Class article should approach the standards for a Featured article (FA), but will typically fall short because of minor style issues. The article may need minor copyedits, but it should be comprehensive, accurate, well-sourced, and reasonably well-written. A peer review should make the article a viable candidate for FA. Assessing an article as A-Class requires a formal written review by more than one impartial reviewer.
Very useful to readers. A fairly complete treatment of the subject. A non-expert in the subject matter would typically find nothing wanting. May miss a few relevant points.
Expert knowledge may be needed to tweak the article, and style issues may need addressing. In particular, issues of breadth, completeness, and balance may need work.Peer-review may help.
Useful to nearly all readers, with no obvious problems; approaching (although not equalling) the quality of a professional encyclopedia. A good treatment of the subject. No obvious problems, gaps, excessive information.
Some editing by subject and style experts is helpful; comparison with an existing featured article on a similar topic may highlight areas where content is weak or missing. If the article is not already fully wikified, now is the time.
The article is mostly complete and without major issues, but requires some further work to reach Good Article standards. B-Class opera articles should meet the six B-Class criteria and a seventh coverage criterion.
The article reasonably covers the topic, and does not contain obvious omissions or inaccuracies. It contains a large proportion of the material necessary for an A-Class article, although some sections may need expansion, and some less important topics may be missing. The article should be neutral and devoid of original research. The article should include illustrations if possible, preferably free images.
The article has a defined structure. Content should be organized into groups of related material, including a lead section and all the sections that can reasonably be included in an article of its kind.
The article is reasonably well-written. The prose contains no major grammatical errors and flows sensibly, but it certainly need not be "brilliant". The Manual of Style need not be followed rigorously.
The article contains supporting materials where appropriate. Illustrations are encouraged, though not required. Diagrams and an infobox etc. should be included where they are relevant and useful to the content.
B-class opera articles should contain a full plot synopsis (with embedded notable arias/musical numbers) that is organized within appropriate divisions. The article should thoroughly cover the Background/history of composition, performance history, musical/textual analysis, critical appreciation, and recordings with no obvious gaps, although some aspects of content and style may still need to be addressed. The opera should be placed into context with other works of the same period, and should include an online libretto if at all possible. Preferably, the article should have illustrations, encompassing musical excerpts and audio in addition to relevant images.
Readers are not left wanting, although the content may not be complete enough to satisfy a serious student or researcher.
A few aspects of content and style need to be addressed, and expert knowledge is increasingly needed. The inclusion of supporting materials should also be considered if practical, and the article checked for general compliance with the manual of style and related style guidelines.
The article is substantial, but is still missing important content or contains a lot of irrelevant material. The article should have some references to reliable sources, but may still have significant issues or require substantial cleanup.
More detailed criteria
The article is better developed in style, structure and quality than Start-Class, but fails one or more of the criteria for B-Class. It may have some gaps or missing elements; need editing for clarity, balance or flow; or contain policy violations such as bias or original research.
C-class opera articles must include a moderately detailed plot synopsis that has sections which reflect the opera's structure and a roles table with the names of original performers. The article should cover the Background/history of composition, performance history, musical/textual analysis, critical appreciation, and recordings; topics which should be informative but not necessarily complete. The article should be referenced to multiple reliable sources but may lack in-line citations or appropriate notes. The article should include relevant external links, particularly to an online libretto. The article may lack illustrations and notable arias.
Useful to a casual reader, but would not provide a complete picture for even a moderately detailed study.
Considerable editing is needed to close gaps in content and address cleanup issues. Some parts may need to be substantially reworded, and editors will need to find more references for many existing sections.
An article that is developing, but which is quite incomplete and, most notably, lacks adequate reliable sources.
More detailed criteria
The article has a usable amount of good content, but it is weak in many areas, usually in referencing. Quality of the prose may be distinctly unencyclopedic, and MoS compliance non-existent; but the article should satisfy fundamental content policies such as notability and BLP, and provide enough sources to establish verifiability. No Start-Class article should be in any danger of being speedily deleted.
Start-Class articles on operas must contain a table of roles with associated voice types (though not necessarily with names of original performers) and a basic plot synopsis that is a minimum of a paragraph in length. The article must provide the date and place of the opera's composition/premiere, the name of the composer/librettist, the opera's genre, and a basic discussion of the opera's structure. The article should provide some contextual information in the following areas (although certain sections may be missing entirely and other sections bairly touched on): Background/history of composition, performance history after the premiere, musical/textual analysis, critical appreciation, and recordings. The article should be referenced to at least one reliable source but may lack in-line citations or appropriate notes. The article should be placed in appropriate categories and may lack illustrations, notable arias, and external links.
Provides some meaningful content, but the majority of readers will need more.
Provision of references to reliable sources should be prioritised; the article will also need substantial improvements in content and organisation.
The article is either a very short article or a rough collection of information that will need much work to become a meaningful article. It is usually very short, but if the material is irrelevant or incomprehensible, an article of any length falls into this category.
Stub-class articles on operas will probably contain minimal contextual information, such as date and place of first performance, and may either give a brief plot summary or a list of roles.
Provides very little meaningful content; may be little more than a dictionary definition
Any editing or additional material can be helpful. The provision of meaningful content should be a priority.
Any list that has not received "Featured lists" status after peer review. The list should meet the criteria of a stand-alone list, which is an article that contains primarily a list, usually consisting of links to articles in a particular subject area.
There is no set format for a list, but its organization should be logical and useful to the reader.
Lists should be lists of live links to Wikipedia articles, appropriately named and organized.