It is a sum of claims by all claimants: creditors (secured and unsecured) and shareholders (preferred and common).
[1] Importantly, EV reflects the opportunistic nature of business and may change substantially over time because of both external and internal conditions.
EV can be negative if the company, for example, holds abnormally high amounts of cash that are not reflected in the market value of the stock and total capitalization.
[2] All the components are relevant in liquidation analysis, since using absolute priority in bankruptcy all securities senior to the equity have par claims.
Value of minority interest is added because it reflects the claim on assets consolidated into the firm in question.
Ideally, multiples should be calculated using the market value of the weighted average capital employed of the company during the comparable financial period.