SharePoint Online can be integrated with an on-prem SharePoint server by leveraging SharePoint Server hybrid. Doing so provides unified functionality and data access to both cloud and on-prem services. SharePoint Server hybrid allows organizations to gradually move their existing on-prem SharePoint Server services to the cloud by providing a staged migration path that extends on-prem SharePoint Server workloads to SharePoint Online. 

Leveraging a SharePoint Server hybrid environment provides trusted communications between SharePoint Online and the on-prem SharePoint Server. With this trust framework in place, you can configure integrated functionality between SharePoint services and features, including search, follow, and even user profiles. 

A hybrid SharePoint environment allows enterprise users to connect to the resources and content that they need, from almost anywhere. Deploying SharePoint hybrid features allows organizations to tie the two environments together in many different ways in order to provide a seamless user experience. 

SharePoint hybrid features allow you to consolidate things, like search results, between SharePoint Server and Office 365. You can also consolidate user profiles in Office 365, while offloading your users' personal storage to the cloud. The hybrid features we'll be covering apply to both SharePoint Server 2013 and SharePoint Server 2016. 

The table that you see on your screen provides an overview of hybrid integration between SharePoint Server and Office 365. You'll see here that, for OneDrive for Business, in a non-hybrid environment, that, although OneDrive for Business is available in Office 365, there's no link to it from SharePoint Server. That said, in cases where MySites is deployed, users can have a second OneDrive for Business in SharePoint Server. In a hybrid environment, OneDrive links, which are available in SharePoint Server, direct users to OneDrive for Business in Office 365. 

As far as the site following feature goes in a non-hybrid environment, the followed sites list in Office 365 tracks followed SharePoint Online sites. However, in cases where MySites is deployed, a second followed sites list in SharePoint Server tracks followed SharePoint Server sites. In a hybrid environment, the followed sites list in SharePoint Online consolidates followed sites from both locations. Users are redirected to the SharePoint Online followed sites list from the followed sites list links in SharePoint Server. 

Regarding document following in a non-hybrid environment, the followed documents list in SharePoint Server tracks followed SharePoint Server documents, provided MySites is deployed. Whereas, in a hybrid environment, document following isn't even available. That said, in cases where hybrid OneDrive for Business is in use, the SharePoint Server followed documents list is hidden from users. 

In a non-hybrid environment, there are separate user profiles in SharePoint Server and in Office 365. Although, in a hybrid environment, while user profiles will exist in both locations, SharePoint Server links to users' profiles will automatically redirect to profiles in Office 365. 

In a non-hybrid environment, users will have two different app launchers. They'll have one in Office 365 and one in SharePoint Server. That said, in a hybrid environment, although there's going to be separate app launchers, the SharePoint Server app launcher includes several tiles from Office 365. 

Now, as far as hybrid self-service site creation goes, in a non-hybrid environment, users will see separate self-service site creation experiences in SharePoint Server and in SharePoint Online. While, in a hybrid environment, users that browse to the default SharePoint Server site creation page, they'll be redirected to the SharePoint Online group creation page. From there, users can create sites in SharePoint Online. In a non-hybrid environment, there are going to be separate search indexes and search centers that exist for SharePoint Server and for Office 365. 

Users must use the SharePoint Server search to find items stored there, and they must use the Office 365 search form to find items stored in Office 365. In a hybrid environment, search results are combined in one of two ways. Cloud hybrid search will crawl on-prem content and index it in the Office 365 search index. As such, users can search the Office 365 index from either location. Hybrid federated search will combine the search results from each search index into a single search center. Now a word about redirection. 

Several SharePoint hybrid features leverage redirection. What redirection does is, when a user tries to access a service in SharePoint Server using site navigation, the user is automatically redirected to the equivalent service in Office 365. 

Let's take, for example, a user named John in a non-hybrid environment. When John clicks OneDrive on a SharePoint Server site, he is taken to his SharePoint Server OneDrive for Business location. However, in a hybrid environment, when John clicks OneDrive, he is taken to OneDrive for Business in Office 365. 

It's important to understand that hybrid OneDrive for Business, hybrid site following, and hybrid profiles all use this redirection technique that sends users from on-prem SharePoint Server solutions to their equivalent services in Office 365. That said, the on-prem SharePoint Server services will continue to function in the background, and they are even accessible by end users who have bookmarked those URLs. 

It's also important to note that redirection does not equal migration. Leveraging redirection does not migrate existing data from SharePoint Server to Office 365. Data contained in OneDrive for Business, along with user profile information, has to be manually migrated for each user. This also means that SharePoint Server followed sites will have to be re-followed as well. Now let's talk a little bit about hybrid site features and OneDrive for Business. 

There are two feature bundles available that help streamline deployment. They are hybrid OneDrive for Business and hybrid sites and features. The hybrid search options are independent of these two bundles and, consequently, are configured separately as well. The table on your screen highlights which hybrid features are included with each option. You can see OneDrive for Business is included in both options, while site following is included only with hybrid site features. Profiles are included in both options. 

The extensible app launcher is part of the sites features in SharePoint Server 2016. However, in SharePoint Server 2013, this feature requires the July 2016 SharePoint update to be installed. Also, it's enabled separately from hybrid sites features by using Windows PowerShell.