Please explain a greedy algorithm in a naive manner
In simple words, an algorithm is normally considered "greedy" if 


it builds solutions step by step without backtracking
in each step it picks what's best in the current state.


To learn more about it, check this pdf out. 





The animated gif above illustrates a greedy algorithm for finding the path that adds up to the biggest number.

It does so by choosing the node with the biggest number at each step. (Since the actual solution is the 7-3-99 path, the greedy approach fails to bring forth the correct path.) 

This is why greedy algorithm may not always yield the right solution to a certain instance of a problem.

The gif animation was created by Swfung8 on Wikipedia for the article on Greedy Algorithm.