There are two types of Minecraft, one is Bedrock, the other one is Java. Bedrock is playable on WIn 10, Xbox One and Mobiles. While the Java can be played on all Windows, Linux, OSX and Free BSD. If you own a Java Minecraft, you can have a free WIn 10 (Bedrock) through this website. http://support.xbox.com/en-US/games/game-titles/minecraft-windows-10-edition-faq#a9355224a14d40d7b82608a6d3f9046d
So, there are technicaly three type of ervers. LAN, Realms and Public. Since there are two types of Minecraft, Bedrock players can play with Bedrock while JAva can play with Java. LAN minecraft can be enabled through settings. Realms can be bought through the MInecraft website. Public servers can be installed in Java through https://minecraft.gamepedia.com/Tutorials/Setting_up_a_server or Bedrock by installing PocketMine/Nukkit.
Hope this will help you!