What is distributed cache Service in SharePoint 2013

The Distributed Cache service provides caching functionality to features in SharePoint Server 2013. The Distributed Cache service is either required by or improves performance of the following features:

• Authentication
• Newsfeeds
• OneNote client access
• Security Trimming
• Page load performance

The microblog features and feeds rely on the Distributed Cache to store data for very fast retrieval across all entities. The Distributed Cache service is built on Windows Server AppFabric, which implements the AppFabric Caching service. Windows Server AppFabric installs with the prerequisites for SharePoint Server 2013.

Any server in the farm running the Distributed Cache service is known as a cache host. A cache cluster is the group of all cache hosts in a SharePoint Server 2013 farm. A cache host joins a cache cluster when a new application server running the Distributed Cache service is added to the farm. When using a cache cluster, the Distributed Cache spans all application servers and creates one cache in the server farm. The total cache size is the sum of the memory allocated to the Distributed Cache service on each of the cache hosts.

The Distributed Cache service can run in dedicated or collocated mode. When running in dedicated mode, the Distributed Cache service is started and all other services are stopped on the server. In collocated mode, the Distributed Cache service is running along with other services on the server.

Some benefits of using microblog features, feeds, and the Distributed Cache include the following:

• Allows users to stay in touch with individuals and specific groups of people over time and distance.
• Allows users to stay informed about what's going in the organization.
• The focus of the interactions is around people or teams, and not so much the topic being discussed.
• It is difficult to keep track of activities related to documents, discussions, and lists in SharePoint without manually visiting the item regularly. Feeds collect and deliver information to users that they would otherwise have to spend time searching for.
• The feed gives users a single place where they can stay up-to-date with all of the content and people they work with.
• Allows quick conversations to take place

MS although strongly recommends that following services should not be run on the server where Distributed Cache Service is running –

SQL Server
Search Service
Excel Service
Project Server

Reference:

http://technet.microsoft.com/library/jj219700(office.15).aspx