What is SEO?

SEO stands for Search Engine Optimization. It is a set of practices/behaviors for your website that help it to stand out and perform better with search engines. And as Google is the 500 lb. gorilla in the search world, they are the ones who set most of the parameters that we follow.

What is an algorithm?
Why are algorithms important?
How do I know what good content is?
How will I know if I'm doing it right?
I'm overwhelmed, what do I do now?