"schema.org is a collaborative, community activity with a mission to create, maintain, and promote schema's for structured data on the Internet." This 'structured data' helps Search Engines to obtain meaningful information from your website, even if this is hidden from the user of the website. This can improve the SEO of the websites you maintain.
Depending on your needs, you could use other, existing, tools for adding schema.org schemas to your website. This tool aims to provide valid HTML markup that can be used to integrate these schema's into your website.
Let's look at a quick example. The first HTML block is generated with this tool, the following two blocks are possible transformations.
For instance
<div itemscope itemtype="http://schema.org/Park">
<div itemprop=geo itemscope itemtype="http://schema.org/GeoCoordinates">
<span itemprop="latitude">44.4279668</span>
<span itemprop="longitude">-110.5906437</span>
</div>
<spanitemprop="hasMap">
http://www.nps.gov/common/commonspot/customcf/apps/maps/showmap.cfm?alphacode=yell&parkname=Yellowstone
</span>
<span itemprop="name">Yellowstone</span>
<span itemprop="url">http://www.nps.gov/yell/index.htm</span>
</div>
can be changed into
<body itemscope itemtype="http://schema.org/Park">
<h1 itemprop="name">Yellowstone</h1>
<div class="geo" itemprop=geo itemscope itemtype="http://schema.org/GeoCoordinates">
Latitude: <span itemprop="latitude">44.4279668</span><br/>
Longitude: <span itemprop="longitude">-110.5906437</span><br/>
</div>
<div class="map">
<iframe itemprop="hasMap"
src="http://www.nps.gov/common/commonspot/customcf/apps/maps/showmap.cfm?alphacode=yell&parkname=Yellowstone">
</iframe>
</div>
<a itemprop="url" href="http://www.nps.gov/yell/index.htm">Go to site</a>
</body>
The hidden keyword can be used to hide some information from the markup, while still allowing Search Engines to find this information.
<body itemscope itemtype="http://schema.org/Park">
<h1 itemprop="name">Yellowstone</h1>
<div hidden itemprop=geo itemscope itemtype="http://schema.org/GeoCoordinates">
Latitude: <span itemprop="latitude">44.4279668</span><br/>
Longitude: <span itemprop="longitude">-110.5906437</span><br/>
</div>
<div class="map">
<iframe itemprop="hasMap"
src="http://www.nps.gov/common/commonspot/customcf/apps/maps/showmap.cfm?alphacode=yell&parkname=Yellowstone">
</iframe>
</div>
<a itemprop="url" href="http://www.nps.gov/yell/index.htm">Go to site</a>
</body>
All three HTML blocks can be validated with the Structured Data Testing Tool .
Multiple schemas can be used simultaneously on one page. For instance, a LocalBusiness can sell different products (OfferCatalog ).