OpenSearch

 OpenSearch  is a specification for search engine discovery and syndication of search results. According to OpenSearch's Introduction, "OpenSearch is a collection of simple formats for the sharing of search results."

OpenSearch descriptions are specifically-formatted XML documents that site authors may link to from within an HTML page. OpenSearch-aware browsers may then allow users to take advantage of the site author's specified search engine.

Why
Adding an OpenSearch specification to a search feature you own means people can query your search engine from their browser navigation bar if they would like. This provides a more convenient interface for search, both for yourself as well as visitors who want to find specific posts or explore your site's content on a particular query.

How
To add OpenSearch to your site search engine, you must first prepare an OpenSearch manifest, like the one seen in the example below. Next, you must add a tag that makes the search specification discoverable.

Manifest Example
  example.com Search example.com.  

The OpenSearch 1.1 Draft specification fully details the required and optional elements that may be included in an OpenSearch description.

Meta Tag Example
Browsers rely on a meta tag or link to discover your OpenSearch manifest. Without the meta tag, browsers will not be able to find where you have saved your manifest.

Here is an example of a meta tag that makes your OpenSearch file discoverable to browsers:



This example is taken from IndieWeb_Search.

You can use the title attribute to specify the name of your search. The rel=search attribute tells your browser that the resource to which you are linking relates to search.

Chromium 48
In the following example, a user has previously visited cweiske.de and Chromium recognizes its OpenSearch description, indicated by the following markup in the page's :



Typing "cweiske.de" in the browser's search bar shows the message, "Press tab to search cweiske.de":



After pressing tab, "Search cweiske.de" in the browser's search bar is presented with a blue background and a user can type a search term:



Pressing return, the user initiates a search and is presented a search results page:



IndieWeb Examples

 * provides an OpenSearch description on http://cweiske.de/, utilizing site search on his own search engine at http://search.cweiske.de.
 * provides an OpenSearch description on sixtwothree.org since 2016-02-15, delegating search to DuckDuckGo.
 * IndieWeb Search provides an OpenSearch description on its website. This search description lets anyone browse IndieWeb Search directly from their browser navigation bar in supported browsers.

Articles
Blog posts and articles about OpenSearch:
 * 2011-07-11 How to let Google power OpenSearch on your website