Hi, this is my first post, so i think it should cover the basics of algorithms.

An algorithm is a detailed instruction of how to do something.

Computers need algorithms because they can`t do anything without them, to simplify computers are only executing orders that are given to them through algorithm that programmer writes.

To write efficient algorithm we first need to understand the problem that algorithm is supposed to solve.
After you understand the problem you should start designing your algorithm (think about the way it will work).
At final you should start implementing it and fix it if it has some bugs.