What is cluster/clustering in simple terms?

Question

Clustering

One project uses Redis, and until I understand it well, I don’t want to use it.
In this regard, I would like to know what cluster / clustering is in simple words.
And if someone can, give an example of how clusters work so that you can visually represent the principle of work.
Thanks in advance!

Answer 1

In simple words: this is when many nodes / machines are used to increase reliability and / or performance, but outwardly it looks like you are using one machine (well, or almost so).
Example: there is a lot of data distributed over several machines. You can find out on which machine the data is by the key. You send a request: give me data on such and such a key, without thinking about whether all the data is stored on one machine or not on one. Klasti will figure it out himself, select the right car, read the data and give it to you.

Answer 2

a cluster is just a lot of servers