Enterprise Value - market cap plus debt, minority interest and preferred shares, minus total cash and cash equivalents - represents the economic value of a company - the minimum amount an acquirer would have to pay to take over the company.
Enterprise value differs from Market Cap in that market cap doesn't fully account for things like cash and debt. For example, a company with a market cap of $100 million and $10 million in cash would really cost $90 million to acquire - because you gain the $10 million with the purchase. Similarly, a company with a market cap of $100 million and $10 million in debt would really cost $110 million to acquire, because you would assume the company's debt when you acquire it.
Enterprise Value is calculated as: