One of the benefits of SharePoint 2013 is its ability to scale property for use in a multitenant environment. In addition to having isolated webs, it also provides for isolation within service applications. This means, that for instance, Company A can have a web that provides search results that are completely isolated from Company B. Of those that can be partitioned, some of the most important are the BDC, Search, Managed MetaData and the Secure Store. Here are the SharePoint 2013 Service Applications that can be partitioned.
The key way SharePoint takes advantage of multi-tenancy capabilities is through Site Subscriptions. Site subscriptions allow grouping of Site Collections of the same Web Application to consume the same features and service information. The key thing to remember is that a site can only have one subscription at a time, and that it has to be managed through powershell. Once a subscription is set up the service application can be partitioned.
To create a new subscription:
$subscription = New-SPSiteSubscription Set-SPSite -Identity http:// mydomain.com/sites/billing -SiteSubscription $subscription
When creating your service application, such as search, add: