The way I usually try to explain it is by saying that an accrual basis looks at what you use. Economists would use a fancier word--they would say something like “consumption”--but it looks at what you use. For example, if you have $10 and you go out and buy something that's worth $10, whether it's sitting there in cash in front of you or whether you have this book, you still have something of value that's worth $10. Accrual basically means let's not worry too much about whether you have the cash or the book; let's worry about what you're using. How much of the wealth that belongs to the taxpayer are we using to run the government? That would be the way I would explain it.
On February 5th, 2009. See this statement in context.