The lead section (also known as the introduction or the lead) of a Wikipedia article is the section before the table of contents and first heading. The lead serves both as an introduction to the article and as a summary of the important aspects of the subject of the article.
The lead should be able to stand alone as a concise overview of the article. It should define the topic, establish context, explain why the subject is interesting or notable, and summarize the most important points—including any notable controversies. The emphasis given to material in the lead should roughly reflect its importance to the topic, according to reliable, published sources, and the notability of the article's subject should usually be established in the first sentence.
While consideration should be given to creating interest in reading more of the article, the lead nonetheless should not "tease" the reader by hinting at—but not explaining—important facts that will appear later in the article. The lead should contain no more than four paragraphs, should be carefully sourced as appropriate, and should be written in a clear, accessible style to invite a reading of the full article.
As explained in more detail below, the lead section may contain optional elements presented in the following order: disambiguation links (dablinks), maintenance tags, infoboxes, images, navigational boxes (navigational templates), introductory text, and table of contents, moving to the heading of the first section.
Correct Structure of Lead Section
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{{Rocket Infobox|name=...}}
[[File:TypicalRocket.gif|...|A typical rocket]] or {{Rocket Navigation}}
A '''rocket''' is a...
[table of contents]
== First section ==
The lead must conform to verifiability and other policies. The verifiability policy advises that material that is challenged or likely to be challenged, and quotations, should be cited. Because the lead will usually repeat information also in the body, editors should balance the desire to avoid redundant citations in the lead with the desire to aid readers in locating sources for challengeable material. Leads are usually written at a greater level of generality than the body, and information in the lead section of non-controversial subjects is less likely to be challenged and less likely to require a source; there is not, however, an exception to citation requirements specific to leads. The necessity for citations in a lead should be determined on a case-by-case basis by editorial consensus. Complex, current, or controversial subjects may require many citations; others, few or none. Contentious material about living persons must be cited every time, regardless of the level of generality.
The lead section should briefly summarize the most important points covered in an article in such a way that it can stand on its own as a concise version of the article. It is even more important here than for the rest of the article that the text be accessible. Consideration should be given to creating interest in reading the whole article. (See news style and summary style.) This allows editors to avoid lengthy paragraphs and over-specific descriptions, because the reader will know that greater detail is saved for the body of the article.
In general, specialized terminology and symbols should be avoided in an introduction. Mathematical equations and formulas should not be used except in mathematics articles. Where uncommon terms are essential to describing the subject, they should be placed in context, briefly defined, and linked. The subject should be placed in a context with which many readers could be expected to be familiar. For example, rather than giving the latitude and longitude of a town, it is better to state that it is the suburb of some city, or perhaps that it provides services for the farm country of xyz county. Readers should not be dropped into the middle of the subject from the first word; they should be eased into it.
In general, the relative emphasis given to material in the lead should reflect its relative importance to the subject according to reliable sources. Significant information should not appear in the lead if it is not covered in the remainder of the article, although specific facts, such as birthdates, titles, or scientific designations will often appear in the lead only, as may certain quotations. This should not be taken to exclude information from the lead, but to include it in both the lead and body: in a well-constructed article, the relative emphasis given to information in the lead will be reflected in the rest of the text. Do not tease the reader by hinting at startling facts without describing them.
The first paragraph of the introductory text needs to unambiguously define the topic for the reader, without being overly specific. It should establish the context in which the topic is being considered, by supplying the set of circumstances or facts that surround it. If appropriate, it should give the location and time context. Also, it must establish the boundaries of the content of the article (for example List of environmental issues is only about the effects of human activity).
The article should begin with a declarative sentence, answering two questions for the nonspecialist reader: "What (or who) is the subject?" and "Why is this subject notable?"[1]