Thanks for this explanation! It is really short and easy.
I have read some sentences about the topic since writing my comment above and @pradeep.sidd68 wrote 5 hours ago that "Nodes that fully verify all of the rules of block chain are called full nodes...
Full nodes ensure the perfection and accountability of block chain transactions.. which not widely understood."

Thanks to both of your explanations, now I have a very basic, brief knowledge about what a node and a full node is.