there are many articles around better describing this. But yes it is money sitting in a savings account, CD, or money market account. Preferably somewhere not directly connected to your checking account and is accessible within 24 hours. If it in your savings account you have at your local bank there won't be much of a interest rate and you will be more likely to tap into it. I have two funds one is in a ING account and one is in a capitol one account both bearing good interest and easy to access in 24 hours if needed. Hope this helps. YOu can look at accounts like ING here:
http://www.bankrate.com/brm/rate/mmm...2&produ ct=33