What is a 401K?

This seems like a simple question, but most people do not completely understand what it is or how exactly it works.

How do I choose the best option?

Most 401K plans offer a ton of investment options as well as account optons, so which one is right for you?

How much should I invest in my 401K?

You are putting money in.  Your employer is putting money in.  But is it enough?

What happens to my 401K when...?

Jobs come, and jobs go.  As we find new employment opportunities what happens with my old 401K?  What are my options?  How do I access the money if I need it?