A blockade is an effort
In physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...

 to cut off food, supplies, war material or communications from a particular area by force, either in part or totally. A blockade should not be confused with an embargo
An embargo is the partial or complete prohibition of commerce and trade with a particular country, in order to isolate it. Embargoes are considered strong diplomatic measures imposed in an effort, by the imposing country, to elicit a given national-interest result from the country on which it is...

 or sanctions
International sanctions
International sanctions are actions taken by countries against others for political reasons, either unilaterally or multilaterally.There are several types of sanctions....

, which are legal barriers to trade, and is distinct from a siege
A siege is a military blockade of a city or fortress with the intent of conquering by attrition or assault. The term derives from sedere, Latin for "to sit". Generally speaking, siege warfare is a form of constant, low intensity conflict characterized by one party holding a strong, static...

 in that a blockade is usually directed at an entire country or region, rather than a fortress or city. Most blockades historically took place at sea, with the blockading power seeking to cut off all maritime transport from and to the blockaded country; although stopping all land transport to and from an area may also be considered a blockade.