Realms

Minecraft Realms is a work-in-progress feature that, put simply, allows players to create and manage their own private server with minimal work and without the hassle of managing a custom server. Hosted by Multiplay through Mojang,, Realms provides an easy and faster way to create Minecraft servers and allows the owner to manage their Realm from inside the game. Do take note, however, that Realms are not intended for large public servers, but for groups of friends or as a family server.

As Minecraft Realms is to the PC edition, Minecraft: Pocket Edition has a similar service, Pocket Realms, which is supported by Amazon and currently is a free limited version available to the same Alpha Testers as the PC version.

Availability
Realms is still in development and is subject to a limited release to certain countries. A subscription can currently only be purchased when living in one of the following countries and regions:

Subscriptions
Unlike most things relating to Minecraft, to get Realms you must subscribe. Depending on which type of subscription you managed to obtain, you will have a different length on your subscription. See the below table for the exact counts.

No matter which type of subscription you obtain, it can be renewed via the link in-game (see Owner's Guide section for more.) If you follow the link, it'll take you to your Mojang account page, where from you can then choose to extend your subscription. Because of this, anyone wishing to buy a Realm must migrate their account to a global Mojang account (visit mojang.com for more info.)

Tutorials
The Realms feature is meant to be simple, but in case you can't figure it out for yourself, refer to the above linked page.

Trivia

 * The Mojang blog closing signature was signed // The Minecraft and Minecraft Realms teams instead of the usual // The Minecraft team starting with the blog Minecraft Snapshot 13w09a.

History
Minecraft Realms has been in development since Minecon 2012, when Mojang revealed that they wanted to host their own servers. At the release of Snapshot 13w09b (released in March 2013,) about 100 active players were selected by a computer algorithm to test the first alpha version of Realms. Later on, with the release of Minecraft 1.6.4, new Alpha Testers were chosen. Also, if you went to Minecon 2013, you received a Minecraft Realms prepaid card, which could be redeemed on Mojang's website for one subscription to Minecraft Realms (the subscription is valid for 30 days). Finally, on December 18, 2013, Minecraft Realms Beta was made available to the public of Sweden. Over the course of that day to the present, Minecraft Realms has become available elsewhere.