This element no longer plays an actual role, because modern browsers allow for one to comfortably and quickly search for text within a displayed HTML file. This element has since been classified as deprecated and soon will no longer be part of standard HTML. The following information has more of a historic character.
A HTML file can be a searchable file. This means that its content can be indexed on the server computer. However, it only makes sense to describe a file as searchable, if its content actually exists on the server computer in the form of a search index file.
With a HTML file that has been defined as searchable, an entry field appears at the beginning after loading the page in a web browser, which allows the user to enter a search keyword.
An Example:
<head>
<isindex prompt= “Please enter a search term: ”>
</head>
Explanation:
You declare a HTML file as searchable with the isindex element. You determine a text for entering a search term with the prompt attribute. The text must be inside the quotation marks.
Take Note:
If you work in XHTML standard, then you have to mark the isindex element as content less. To do so, notate the standalone tag in this format: <isindex … />.