What is the best way to store large "world" data?

I was planning on making a blocky terrain system like Minecraft has, and was wondering how the information for such a map would be stored. Information like which block type is at a given position. Would you store it in an array, or is there a faster and easier approach for handling large amounts of data like this and saving it?

If you search the forum (or use Google to do it) for minecraft of voxel worlds you’ll probably find the information you are looking for. The topic has been discussed numerous times.

I’d also bet this inexpensive udemy course would include plenty of information on the topic as well:
https://www.udemy.com/unityminecraft/