See: Debt-to-EBITDA. See: Net Debt.
Why "net" and not just "debt to"? Because companies usually keep around a fair pot of cash. And in a Debt-to-EBITDA calculation, we're really worried about leverage ratios and covenants, i.e., if the company's EBITDA drops too low in a bad business run, will bad convenants be triggered, and blam-wham-flim-fam...the bank then owns the company?
As equity investors, we uh...don't want that. So we look at debt minus cash when we think about this ratio.
Whatever.com has $300 million in debt and $120 million in cash. We think of them as having $180 million in net debt. So if their EBITDA this year is $50 million, against gross or total debt, it'd be a scary 6x ratio, but against net debt of $180 million, it's a 3x ratio...not nearly as death-kissy.