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 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.

Availability
Realms is still in development and is subject to a limited release in 101 countries. A subscription can currently only be purchased when living in one of the following countries and regions:

Subscriptions
Manage your subscriptions here.

Realms is a service that requires you to buy a subscription and renew it every time your current one expires. To do this, go to the link above, and it will let you purchase a subscription (check the Availability section to see if you can buy it.)

Here are the types of subscriptions and how long they last:

Managing a Realm
If you own a Realm, it can sometimes be slightly confusing what buttons do what. Here is a quick overview of the Realms menu:

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.

Issues
The best way to report Realms bugs is to email the Realms support address, linked in the infobox above.