wikipedia-global-site-search-form.html

<form action="/w/index.php" id="searchform">
    <div id="simpleSearch">
        <input type="search" name="search" placeholder="Search" 
        title="Search Wikipedia [ctrl-option-f]" accesskey="f" id="searchInput" tabindex="1" 
        autocomplete="off">
        <input type="hidden" value="Special:Search" name="title">
        <input type="submit" name="go" value="Go" 
        title="Go to a page with this exact name if it exists" id="searchButton" 
        class="searchButton">
    </div>
</form>