Minecraft Realms are private servers that players can enjoy together - always online and freely accessible... but not free to access, as Realms are a paid feature in Minecraft, meaning subscription fees.
The draw here is that Realms are special private servers that don't require a host, are always online, and up to 10 players can be members, dropping into this shared world whenever they like and regardless of who else is online. it's one of the more helpful features in Minecraft, which will go some way to explaining why it's locked behind a paywall. Still, if you want further details, here's everything you need to know about Minecraft Realms - the limitations, the details, the prices, and how to set one up.
